This manual is provided to you in electronic format.  It is supplied for 
the sole purpose of documenting and supporting Mult-Tech Systems' 
products.  Any translation, modification, or unauthorized copying of 
this manual is strictly prohibited.  The information contained herein is 
protected by U.S. copyright laws and international treaties.

This text only manual is based on the MT2834MR owners manual, 
P/N 82035702, Rev. C.

1.1     Introduction

Welcome to the world of data communications. You have acquired one 
of the finest rack-mount intelligent modems available, the MT2834MR, 
from Multi-Tech Systems.  This owner's manual will help you install, 
configure, test, and use your modem.  

Your MT2834MR is designed to operate in two modes.  First, it 
functions as a 28,800 bps leased line modem with dialback security.  
Communications over leased lines have been popular for many years 
primarily over 4-wire lines using V.29 modulation techniques.  There 
have been dial back-up features in some leased line modems, but the 
dial back-up was at a slower speed. Your MT2834MR uses V.34 
modulation that is designed for full 28,800 bps full duplex operation 
over 2-wires.  That means when the MT2834MR uses its dial back-up 
capability, performance does not suffer.

The second MT2834MR mode of operation is as a standard ITU-T 
V.34 2-wire dial-up modem.  As such, it has incorporated all the 
advanced features of other Multi-Tech intelligent modems.
This manual documents all of the MT2834MR's features and 
capabilities, such as autodial, auto-answer, auto-fallback, number 
linking, option switches, phone number memory, call progress 
detection, and more. The next section will show you how to use this 
manual. The contents of each chapter are listed, so you will know where 
to turn for specific information.

1.2     How To Use This Manual

This manual is divided into eight chapters. There are also several 
appendices at the end of the manual, most of which repeat information 
contained in the chapters, but in a more condensed form. The 
information contained in each chapter and appendix is as follows:

Chapter 1 - Introduction & Description
This chapter begins with a short introduction, followed by a guide 
(which you are now reading) to the use of the manual. We then provide 
a more detailed description of the modem, as well as a chart containing 
the modem's technical specifications. This is then followed by sections 
covering power, LED indicators and a brief summary of modem switch 
options. (Chapter 7 covers switch settings more thoroughly.)

Chapter 2 - Dialing and Answering
This chapter covers Answer mode operation in detail, as well as the 
handshaking procedures between two modems and an auto-answer 
application. Various methods of call termination are also discussed.

Chapter 3 - Command Mode Operation
This may be the most important chapter of this manual. It begins with 
an introduction and discussion of the MT2834MR's Command mode 
fundamentals. A flow chart is provided to illustrate Command mode 
and On-Line mode operation and the methods used to enter each mode. 
Next, there is a summary of the modem's commands and responses. We 
then go into a detailed explanation of each command, providing 
examples where applicable.

Chapter 4 - S-Registers
This chapter covers the MT2834MR's S-Registers, which are used to 
store and/or configure various modem options. All of the S-Registers 
are defined and explained, followed by instructions on accessing the S-
Registers and reading or changing their values.

Chapter 5 - Error Correction, Data Compression and Speed Conversion
This chapter provides information concerning some of the advanced 
features of the MT2834MR. Features such as V.42 Error Correction, 
MNP 5 Data Compression, Speed Conversion and others enable your 
MT2834MR to operate at a higher level of efficiency than possible with 
standard AT command set features.

Chapter 6 - Testing Your Modem
This manual does not cover testing.  For test information, refer to your 
MultiModemManager Owner's Manual.

Chapter 7 - DIP Switches and Jumpers
The MT2834MR's printed circuit board options are covered in this 
chapter. The DIP switch settings and on-board jumper plugs are 
explained in detail, including all default settings.

Appendix B - Dial Pulses and Tone Dial Frequencies

Appendix C - DIP-Switch Summary

Appendix D - Result Code Summary

Appendix E - S-Register Summary

Appendix F - AT Command Summary

Appendix G - V.25bis Operation

Appendix H - RS232C Interface Specifications

Appendix J - Escape Sequences Used by Multi-Tech Systems

Appendix K - Remote Configuration

1.3     Description

Each MT2834MR card has three integrated 28,800 bps MultiModems. 
Each of the three modems on the MT2834MR card can be configured 
independently from each other via the MultiModemManager (Model 
#MR4800). The rack can support and control up to 16 MultiModem 
cards, to a total of 48 modems per rack. Up to 254 racks can be 
networked, for a total of 12,192 modems on the network under control 
of a single PC. Refer to your MultiModemManager Owner's Manual for 
more information on the rack and its components.

Perhaps the most significant extras incorporated in the MT2834MR are 
its V.42 error correction and V.42bis data compression features. With 
error correction and data compression, transmission errors are 
eliminated while increasing the modem's throughput by a ratio of up to 
4:1, for an effective overall transmission rate approaching 115,200 bps.

The MT2834MR offers interactive automatic dialing capability, as well 
as Command Mode option configuration. Up to ten command 
line/telephone numbers, of up to 60 digits each, can be stored in the 
modem's non-volatile memory. The modem uses pulse and/or tone 
dialing methods, and has the ability to recognize dial tones and busy 
signals for reliable call-progress detection.

The MT2834MR is FCC-Registered for direct connection to the public 
telephone networks. No Data Access Arrangements (DAA's) are 
required.

The MT2834MR is fully compatible with the Standard AT command 
set, and is therefore compatible with all of the popular communications 
software packages.

1.4     FCC Regulations for Telephone Line                      
	Interconnection

1.      No repairs are to be made by you. Repairs are to be made only 
	by Multi-Tech Systems or its licensees. Unauthorized 
	repairs void registration and warranty. Contact 
	Multi-Tech Systems, Inc. for details of how to have repairs 
	made.

2.      When trouble is experienced, you must disconnect your 
	modem from the telephone company's jack to determine the 
	cause of the trouble, and reconnect your modem only 
	when the trouble is corrected.

3.      The modem cannot be connected to pay telephones or party lines.

4.      If requested by the telephone company, you must notify them 
	of the following before the MT2834MR is installed:

	a. The particular phone line (phone number) to which the        
	connection is to be made.

	b. The FCC Registration Number: AU7USA-20673-MM-E

	c. The Ringer Equivalence: 0.3B

	d. Modems can only be connected to the phone lines 
	through standard modular jacks. The Uniform Service Order Code                              (U.S.O.C.) for 
	the standard modular jack which connect the             
	modem to the phone lines are:
	
	RJ11C or RJ11W (single line)

	e.  The manufacturer's name and model number:   
	Multi-Tech Systems - Model MT2834MR

5.      If the telephone company notifies you that your device is 
	causing harm, unplug it. The telephone company may disconnect your 
	service if necessary and also may change its facilities, equipment, 
	operations or procedures which may affect operation of your 
	equipment. Where practical, the telephone company must promptly 
	inform you in writing of the temporary disconnect or change in service, 
	give you the opportunity to make changes allowing uninterrupted 
	service, and inform you of your rights to bring a complaint to the FCC.

1.5     Canadian Limitations Notice

NOTICE: The Canadian Department of Communications label 
identifies certificated equipment. This certification means that the 
equipment meets certain telecommunications network protective, 
operational and safety requirements. The Department does not 
guarantee the equipment will operate to the user's satisfaction.
Before installing this equipment, users should ensure that it is 
permissible to be connected to the facilities of the local 
telecommunications company. The equipment must also be installed 
using an acceptable method of connection. In some cases, the 
company's inside wiring associated with a single line individual service 
may be extended by means of a certified connector assembly (telephone 
extension cord). The customer should be aware that compliance with 
the above conditions may not prevent degradation of service in some 
situations.

Repairs to certified equipment should be made by an authorized 
Canadian maintenance facility designated by the supplier. Any repairs 
or alterations made by the user to this equipment; or equipment 
malfunctions, may give the telecommunications company cause to 
request the user to disconnect the equipment.

Users should ensure for their own protection that the electrical ground 
connections of the power utility, telephone lines and internal metallic 
water pipe system, if present, are connected together. This precaution 
may be particularly important in rural areas.

The Load Number (LN) assigned to each terminal device denotes the 
percentage of the total load to be connected to a telephone loop which 
is used by the device, to prevent overloading. The termination on a loop 
may consist of any combination of devices subject only to the 
requirement that the total of the Load Numbers of all the devices does 
not exceed 100. The Load Number for this product is 5.

CAUTION:  Users should not attempt to make such connections 
themselves, but should contact the appropriate electric inspection 
authority, or electrician, as appropriate."

This digital apparatus does not exceed the Class A limits for radio noise 
for digital apparatus set out in Department of Communications.

1.6     Compliance with BABT Requirements                       
	(MT2834MRK only)

European Low Voltage Directive

When correctly installed and maintained, the modem will present no 
hazard to the user. When correctly installed the modem will be 
connected to the PSTN or a PW and to a Data Terminal Equipment 
(DTE), whose modem connections comply with ITU-T 
recommendation V28. The DTE connections are therefore taken to be 
safe voltages (less than +30 volts).

Approved for connection to telecommunications system specified in the 
instructions for use subject to the conditions set out in them Approval 
no. NS/3422/23/N/603030 (Model #MT2834MRK).

Compliance with BS6305 Clause 6.2 BS6320 Clause 7.2 and 
BABT/SITS/82/005S/D

a.      The modem is suitable for connection to the Public Switched     
	Telephone Network (PSTN) provided by British    
	Telecommunications pic or Kingston Communications (Hull) plc.              Circuit supply by British 
	Communications, Mercury Communication or Hull City Council. 
	Only direct exchange lines may be used, not shared service. 
	The modem may be connected to private speech band. 

b.      The modem is suitable for household, office and similar 
	general indoor use. It is not suitable for use as an extension to 
	a payphone.

c.      BT lines supplied must support either loop disconnect or        
	multifrequency tone signalling.

d.      REN (Ringer Equivalence Number).
	The REN value of a unit is calculated from 3/n where n is the total 
	number of units which can be connected in parallel which will still 
	cause the standard bell (as defined in BS6305 Appendix D) to ring. 
	REN values of less than 0.3 cannot be assigned. 

For apparatus which is not capable of forming part of a multiple 
installation, a REN value of 3 is assigned.

			REN = 1

If a telephone or other device is connected in parallel with the modem, 
the combined REN must not exceed 4. A BT supplied telephone may be 
assumed to have REN of 1.0 unless otherwise noted.

The approval of this modem for connection to the British Telecom 
public switched telephone network is INVALIDATED if the apparatus 
is subject to modification in any material way not authorized by BABT 
or if it is used with or connected to:

i.      internal software that has not been formally accepted 
	BABT.

ii.     external control software or external control apparatus 
	which cause the operation of the modem associated 
	call set-up equipment to contravene the requirements of the 
	standard set out in BABT/SITS/82/005S/D.

All apparatus connected to this modem and thereby connected directly 
or indirectly to the British Telecom public switched telephone network 
must be approved apparatus as defined in Section 22 of the British 
Telecommunications Act 1984.

Compliance with BS6789: Section 3.1 and Part 2

a.      The modem is not capable of allowing Auto Call using '999' or 
	other PABX emergency numbers.

b.      Modes, other than modes 1,2 or 3 should not be used on the 
	BT PSTN. This modem is a mode 1 device.

c.      Users are advised to check the numbers entered during the 
	AutoCall set up phase prior to dialing.

d.      The user should not issue any sequence of commands to the       
	modem which would cause the modem to exceed the 
	maximum allowable pause of 8 seconds from the time 
	the modem goes off hook until dialing begins.

Compliance with BS6328 Part 1 and BABT/SITS/82/01/C (Use on 
Private Circuits)

a.      The modem is not suitable for use on circuits with British      
	Telecommunications signaling at a nominal frequency 
	of 2280Hz.

b.      The modem does not require signaling or otherwise employ 
	the frequency range dc to 200Hz.

c.      The modem may be connected directly to a point-to-point two-    
	wire or four-wire Private Circuit.

d.      The modem does not require dc from the Private Circuit for      
	correct operation. The modem may be damaged if 
	connected, in private circuit mode, to a circuit supplying 
	dc current (the maximum permissible direct 
	current is zero amps).

e.      The approval of this modem for connection to British Telecom 
	Private Speech band circuits is INVALIDATED if 
	the apparatus is subject to any modification in any material 
	way not authorized by BABT or if it is used with, or 
	connected to:

	i)      internal software that has not been formally accepted 
		by BABT.

	ii)     external control software or external control 
		apparatus which cause the operation of the modem 
		or associated call set-up equipment to contravene 
		the requirements of the standard set out in 
		BABT/SITS/82/01/C.

All apparatus connected to this modem and thereby connected directly 
or indirectly to British Telecom Private Speechband circuits must be 
approved apparatus as defined in Section 16 of the British  
Telecommunications Act. 1981.

Compliance with DTI 83/009

a.      The apparatus is only approved for compatible PBXs. Consult     
	the supplier for an up to date list of compatible PBXs.

b.      There is no guarantee of correct working in all circumstances.  
	Any difficulties should be referred to Multi-Tech.

c.      If sockets are required for connection to the PBX, use the BT   
	post card only if BT owns the wiring to the PBX.

This apparatus has been approved for the use of the following facilities:
	*Auto-calling
	*Loop disconnect and MF dialing
	*Phone number storage and retrieval by
	 a predetermined code
	*Operation in the absence of proceed indication
	*Detection of initial and secondary proceed indication
	*Automatic storage of last number dialed
	*Tone detection-busy
	*Auto clear from the originating end 
	*DTR dialing 
	*Modem
	*PBX timed break register recall

Any other usage will invalidate the approval of the apparatus if as a 
result, it then ceases to comply with the standards against which 
approval was granted.

1.7     Technical Specifications

Tradename               MultiModemV34

Model Number            MT2834MR, MT2834MRK, MT2834MRI

Data Rates (bps)        Three independent modems(Modem A, B, C) 
			each operating at 28,800, 26,400, 24,000, 
			21,600, 19,200, 16,800, 14,400, 12,000, 
			9600, 4800, 2400, 1200, or 0-300 bps

Data Format             Serial, binary, asynchronous at 0-300, 1200,    
			2400,4800, 9600, 14,000, 16,800, 19,200, 
			21,600, 24,000, 26,400,or 28,800bps; 

			synchronous at 1200, 2400, 4800, 9600, 14,400, 
			16,800,19,200, 21,600, 24,000, 26,400, or 28,800 bps.

Configuration           Each of the card's 3 modems are                 
			independently configurable

Compatibility           ITU-T V.42, V.42bis, V.34, AT&T V.32terbo, 
			ITU-T V.32, V.32bis, V.25bis, V.21, V.22bis, 
			V.22, V.23, V.17, Bell212A* and 103/113*

Error Correction        MNP Classes 2, 3, 4, and LAPM

Data Compression        MNP 5, and V.42bis

Speed Conversion        Serial port data rates adjustable to 300, 
			1200, 2400, 4800,9600, 19,200, 38,400, 57,600, 
			115,200 bps

Flow Control            Xon/Xoff, Hardware CTS/RTS, ENQ/ACK

Mode of Operation       Full over both dial-up lines and 2-wire or 4-
			wire leased lines; automatic Dialback-up on     
			separate lines in leased line operation, in              dial-up mode; automatic or manual dialing,      
			automatic or manual answer.

Intelligent Features    "Standard AT" command compatible, autodial,       
			redial, repeat dial*, dial linking*, pulse or tone 
			dial, dial pauses, call status display, auto-     
			parity and data rate selection, keyboard-                      controlled 
			modem options, non-volatile memory, Caller ID 
			(optional feature), and on-screen displays for 
			modem option parameters and up to ten telephone 
			numbers/command lines of up to 60 digits each, 
			help menus, remote configuration, and V.25bis dialing.

Commands                100% compatible with "Standard AT"
Compatibility           Command Set

Command Buffer          60 characters

Automatic Dialing       Choice of "Standard AT" command asynchronous dialing, 
			"AT" command-controlled asynch-to-synch DTR dialing, 
			or ITU-T V.25bis Synchronous or Asynchronous dialing.

Automatic Leased        When in dial back-up mode, modem will 
Line Restoral           attempt leased line restoral periodically       
			according to software configuration.

Modulation              Trellis Coded Modulation (TCM) at 28,800, 26,400, 
			24,000, 21,600, 19,200, 16,800, 14,400, 12,000, 
			and 9600 bps; QAM at 9600 (non-trellis), 4800 and 
			2400 bps, PSK at 1200 bps, FSK at 300bps

Carrier Frequencies     Transmit Originate:     1200 Hz
  2400 & 1200 bps       Transmit Answer:        2400 Hz
  (V.22 or Bell 212A    Receive Originate:      2400 Hz
  Standard)             Receive Answer:         1200 Hz

Carrier Frequencies,    1270 Hz Mark, 1070 Hz Space for
  300 bps*              Transmit Originate
  (Bell Standard)       2225 Hz Mark, 2025 Hz Space for
			Receive Originate
			2225 Hz Mark, 2025 Hz Space for
			Transmit Answer
			1270 Hz Mark, 1070 Hz Space for
			Receive Answer

Carrier Frequencies     980 Hz Mark, 1180 Hz Space for
 V.21                   Transmit Originate
			1650 Hz Mark, 1850 Hz Space for
			Transmit Answer
			1650 Hz Mark, 1850 Hz Space for
			Receive Originate
			980 Hz Mark, 1180 Hz Space for
			Receive Answer

 V.23                   390 Hz Mark, 450 Hz Space for
			Transmit Originate
			1300 Hz Mark, 2100 Hz Space for
			Transmit Answer
			1300 Hz Mark, 2100 Hz Space for
			Receive Originate
			390 Hz Mark, 450 Hz Space for
			Receive Answer

Carrier Frequencies     1800 Hz (V.32)
  V.32 and V.32bis

Fax Modulations         V.21CH2 FSK at 300 bps
			V.27ter DPSK at 4800 and 2400 bps 
			V.29 QAM at 9600 and 7200 bps 
			V.17 TCM at 14400, 12000, 9600, and 7200 bps

Fax Carrier             V.21 CH2 (Half Duplex)
Frequencies             1650 Hz Mark. 1850Hz Space for 
			Transmit Originate
			1650 Hz Mark, 1850Hz Space for 
			Transmit Answer
			V.27ter 1800 Hz Originate/Answer
			V.29 QAM 1700 Hz Originate/Answer
			V.17TCM 1800 Hz Originate/Answer

Transmit Level          -10 dBm (dial-up) 0 dBm (leased line, MT2834MR) -
			13 dBm (private wire MT2834MRK) -11dBm (MT2834MRI)

Note:   The Transmit Values apply to the domestic, U.K., and the 
standard International defaults only, country-specific modems may 
vary.

Frequency Stability     +0.01%

Receiver Sensitivity    -43 dBm under worst case conditions

AGC Dynamic             43 dB
Range

Interface               EIA RS232C

Diagnostics             On-line Diagnostics 
			ITU-T V.54 Remote Loop, V.54 Digital Loop (with or 
			without Pattern Generator)

			Offline Diagnostics
			ITU-T V.54 Analog Loop, Self-Tests
			Automatic Diagnostics
			Dial-up Tests

Firmware Upgrades       via Flash PROM technology on Multi-Tech's 
			BBS

Indicators              LEDs for Transmit Data, Receive Data, Carrier 
			Detect, 28,800 bps, 24,000 bps, 19,200 bps, 
			14,400 bps, 9600 bps, 2400 bps, Off Hook,      
			Data Terminal Ready, Test and Out-Of-Service, 
			Fax and Error Correction.

Controls                Toggle switches for Busy;  DIP-Switches for
			various modem options.

Operating               0 deg. to 50 deg. (32 deg. to 120 deg. F)
Temperature

Power                   5 Volts DC at 0.95 Amp 
Requirements            +/-16 Volts DC at 0.1 Amp

Power Consumption       Approximately 6 watts

Dimensions,             .9"x11"x15" (2.2x28x37 cm) HxWxD 
card modem

Weight                  2.5 Lbs. (1.1Kg)

Limited Warranty        Two Years

Fuses                   F1 (+5V), F2 (-16V), F3 (+16V)

1.8     Power

DC voltages are supplied to all of the modems in the CC4800 rack 
through one or two PS4800 power supplies, designed for conventional 
115 or 230 VAC connection. The power supply is a universal input 
switching power supply.

1.9     Modem LED Indicators

The MT2834MR has fifteen LED indicators. They are:

1.      Transmit Data (XMT). This LED blinks when data is being         
	transmitted, on for a space, off for a mark. The state 
	of this LED matches that of the XMT circuit on Pin 2 of 
	the RS232C interface.

2.      Receive Data (RCV). This LED blinks when data is received, 
	on for a space, off for a mark. The state of this LED 
	matches that of the RCV circuit on Pin 3 of the RS232C 
	interface.

3.      Carrier On (CD). This LED lights when a valid carrier tone 
	has been detected.

4.      28,800 bps (28.8K). This LED lights when the modem is set 
	for 28,800 bps operation.

5.      24,000 bps (24K). This LED lights when the modem is set for     
	24,000 bps operation.

6.      19,200 bps (19.2K). This LED lights when the modem is set 
	for 19,200 bps operation.   

7.      14,400 bps (14.4K). This LED lights when the modem is set 
	for 14,400 bps operation.

8.      9600 bps (96). This LED lights when the modem is set for 
	9600 bps operation.

9.      2400 bps (2400). This LED lights when the modem is set for      
	2400 bps operation. If the 2400 or 9600 indicators 
	are not on, this indicates that the modem is set 
	for 300 bps operation.

10.     Off Hook (OH). This LED lights when the phone line is "off 
	hook." 		This will occur when the modem is dialing, on line, or 
	answering a call. The indicator will also flash when the 
	modem is pulse dialing in Command mode.

11.     Data Terminal Ready (DTR). When the DTR LED is lit, the         
	modem is permitted to answer an incoming call. 
	When it goes off, a connected modem will disconnect. The 
	state of this LED matches that of the DTR circuit on Pin 20 of 
	the RS232C interface.

12.     Error Correction (V.42). This LED lights when the modem is 
	in error correction mode, and flashes on and 
	off when data compression is enabled.

13.     Fax (Fax). This LED lights when the modem is in Fax mode.

14.     Test Mode (Test). This LED lights during test mode              
	operation.  With the optional MultiModemManager 
	Software installed, a full suite of modem tests 
	can be controlled from a central PC. Refer to the 
	MultiModemManager Owner's Manual for more test 
	information. The Test LED lights during any of the      
	software-control diagnostic tests.

15.     Out-Of-Service (OOS). When the OOS LED is flashing, the         
	leased line is down and the modem is in dialback 
	mode or the self-test has failed. When OOS LED is 
	continuously lit, the modem is in busy out/out 
	of service (OOS) state.

Note:   The PS4800 modem rack power supply has one LED that     
	indicates the presence of all supply voltages.

1.10    BUSY Switch

The MT2834MR contains three two-position BUSY switches on the 
front panel. Each switch can be used to create a "busy out" (OOS) 
condition for one of the three on-board modems (i.e., Modem A, B, or 
C).

To place a modem in the Busy condition, move the appropriate BUSY 
switch to the right. The selected modem goes off-hook, its OOS and OH 
LEDs light, and incoming calls to this modem get a busy signal. If you 
suspect a problem with a particular modem, you can use the BUSY 
switch to have an optional device (such as a "hunt group") that looks for 
a non-busy line to perform a "roll over" to the next available modem 
while you check the status of the Busy modem.

NOTE:   The MultiModemManager can perform the same function     
	using software.

1.11    Controls on PC Board

The MT2834MR modems contain three 16-position DIP-Switches and 
several jumper plugs. The DIP-Switches control various modem options 
or set default values for Command mode operation.

There are also "jumper" option settings on the circuit board, which 
control V.54/Test (OOS) functions.

The toggle switch positions on the MT2834MR are be labeled "Busy" 
for each of the three on-board modems (Modems A,B,C).

Chapter 7 of this manual provides detailed instructions on configuring 
all of the MT2834MR's DIP-Switches and jumpers.

1.12    MT2834MRK Installation Notes

The installation instructions include information about the use of 
blanking plates to cover empty slots in the card frame. Be sure to follow 
the instructions on installation that are provided in your 
MultiModemManager Owner's Manual.

Warning: Interconnection directly, or by way of other apparatus, of 
ports marked 'SAFETY WARNING see instructions for use' with ports 
marked or not so marked may produce hazardous conditions on the 
network. Advice should be obtained from a competent engineer before 
such a connection is made.

This product is intended to be hard wired to the network. The final 
connection to the network is the responsibility of the public 
telecommunications network operator or a person authorized by that 
operator.

Any other apparatus, including cable and wiring, connected between the 
MT2834MRK modem and the point of connection to any speechband 
circuit shall comply with the following:
	
(1)     the overall characteristics of this apparatus shall be 
	such as to introduce no material effect upon the 
	electrical conditions presented to one another by the modem 
	and the speechband circuit;
	
(2)     the apparatus shall comprise only;
	
	(a)     apparatus approved (see note) for the purpose                           
	of connection between the modem and a speechband circuit; and
	
	(b)  cable and wiring complying with a code of practice for 
	the installation of equipment covered by this part of BS 6328 
	or such other requirements as may be applicable.

Note: Such apparatus may have been approved subject to limitations in 
its use.

2.1     Introduction

This chapter describes the dialing and answering capabilities of the 
MT2834MR. Since the modem can be either a leased line with dialback 
modem or a standard ITU-T V.34 full duplex dial-up modem, both 
modes are described (in terms of dialing features) in this chapter.

2.2     Automatic Leased Line Restoral Operation

When the MT2834MR is in the dial back-up mode of operation, it will 
periodically check the leased line to see if it's operational and try to 
restore the leased line if possible. This is the automatic leased line 
restoral feature.* The frequency of the restoral feature attempts are 
determined by the contents of S-Register S18. The default for S18 is 30 
minutes and can be set in one minute increments from 10 to 255 
minutes. Setting the restoral frequency under 10 minutes causes 
excessive breaks in the dial-up operation.

2.3     Manual Dial Backup Call Termination

If your MT2834MR is in the leased line mode (DIP Switch #10 in the 
Down ("Closed") position) and with a dial back-up operation in 
process, there are two ways to manually terminate (other than automatic 
leased line restoral) the dialback call. In each of these cases, you will be 
attempting to establish the leased line connection because it is back in 
operating condition. 

* Both local and remote modems should have S-Register S18 set 
identically.

The methods of dial-back call termination are:

1.      DTR Control. If DTR (Data Terminal Ready) is turned off for 
	50 milliseconds or more, a disconnect will occur. This is 
	probably the most common method used by computer 
	systems at the automatic answer end of the line to 
	cause the answering modem to disconnect after logging 
	off procedures.

2.      Command Mode Control. It is possible to enter Command   
	Mode while remaining on-line by entering the Escape 
	Sequence (+++AT<CR> in most cases). After you 
	have entered Command mode,  you may either return to the 
	On-Line by typing ATO, or terminate the call with the 
	H command. Typing ATH will hang up the line (bring it 
	on-hook), bringing the modem out of the On-Line mode. 
	So, the command to hang up a call is three plus signs,  
	and then ATH.

3.      Loss of Carrier. After a data connection has been established,  
	the modem will disconnect if a loss of carrier occurs for 700   
	milliseconds (.7 seconds) or more. The 700 mSec 
	time can be configured for any time from 0 to 25.5 
	seconds, in 100 mSec increments, with S-
	Register S10. Note that one cause of carrier loss would be if 
	one of the modems were to disconnect normally. S10 
	works for speeds of 2400 bps or below, otherwise carrier        
	loss will take about 20 seconds in a V.34 connection.

2.4     Dial Back-up Leased Line Restoral

The dialing associated with the MT2834MR when it's operating in 
leased line with dialback mode, involves the placing of a call from the 
originating modem due to a leased line failure. The call can be placed 
automatically by the modem when the below described conditions are 
met. The dialback condition is indicated by the OOS LED blinking. 
After a preset period of time (determined by S-Register S18), the 
modem will try and restore the leased line automatically.
The parameters used to determine whether a leased line is down (so that 
automatic dialback can occur), is based on the MT2834MR doing a 
retrain on the leased line due to an error condition in the transmission. 
An error condition is defined as a "hit" on the line (the Carrier gets 
interrupted).

The retrain is a "handshake" procedure between the modems to 
establish the Carrier again. If the retrain fails, both modems (originate 
and answer modems) start their Dialback timers. The time is determined 
by the setting of S-Register S19. The default for the time is one minute. 
During that minute, the originate modem will try to establish the leased 
line link. If during that time, the leased line is established, the timer is 
cleared and everything is back to normal. If the timer expires the 
modems will go to dialback mode.

The purpose of the timer for the Answer modem is to determine when it 
will accept a dial-up call. When both timers have expired and the leased 
line has not been established the dialback procedure will start. The 
number dialed is the one stored in location N9 of the originate modem's 
phone number memory. In preparation for proper dialback operation, 
you must enter the proper number in the N9 location using the 
commands detailed in Chapter 3. Keep in mind that the number also can 
be a V.25bis command for synchronous operation.

2.5     Dial-up Automatic Answering

With your MT2834MR in the dial-up mode (12-Position DIP Switch 
#10 in the UP position), the MT2834MR can be used as an automatic 
answering modem.

The MT2834MR, when in its idle state, will be set up with originate 
mode frequencies. An incoming ring signal will automatically switch 
the modem into answer mode.

You can program the modem to answer a call after a certain number of 
rings by using the modem's S-Register S0. (See Chapter 4).  Refer to 
Section 2.6 for the handshaking procedures used by the MT2834MR in 
an automatic answering application.

2.6     Dial-up Handshaking Details

With your MT2834MR in the dial-up mode (12-Position DIP Switch 
#10 in the UP position), the following briefly explains what happens 
between two modems in a normal call. We are assuming that there are 
MT2834MR's at both the originating and at the answering end of the 
telephone line. (If other brands of modems are used with our modems, 
they will still communicate, but each manufacturer tends to use slightly 
different delay timings and sequences, and many of the brands vary in 
their LED designations.)

Before V.34 negotiation takes place, remote and local modems transfer 
their functional capabilities using modulated calling and answering 
tones.  First, the Calling Menu (CM), a data sequence using V.21 low-
band modulation (a handshaking technique originally developed for 300 
bps modems), is sent from the originating V.34 modem to the 
answering V.34 modem.  This describes the range of functional 
capabilities the originating modem supports.  The answering V.34 
modem responds to the CM with a Joint Menu, or JM (using V.21 high-
band modulation), indicating the common capabilities of the modem at 
each end.

Once this is done, a probing signal is passed between the modems to 
identify impairments in the telephone channel.  After receiving the 
results of the probing signal, the modem receivers and transmitters will 
start with the lowest speed and move up until reaching the highest speed 
at which they can exchange data.  All this occurs in about five seconds.
Note: In order for the called modem to be able to answer the call, it 
must have a high DTR (Data Terminal Ready) signal. This signal comes 
from the computer or terminal to which it is attached, on RS232C Pin 
20, or it can be forced on by a switch in the modem.

Note: If you are using the Reliable or Auto-Reliable mode, some 
additional handshaking takes place. This is explained in Chapter 5, in 
the "Auto-Reliable Mode" section.

2.7     Call Termination

With your MT2834MR in the dial-up mode (12-Position DIP Switch 
#10 in the UP position), there are a number of methods by which you 
can terminate a call, or simply stated, hang up. They are:

1.      Command Mode Control. It is possible to enter Command   
	Mode while remaining on-line by entering the Escape 
	Sequence (+++AT<CR> in most cases). After you 
	have entered Command Mode, you may return to the On-
	Line state by typing ATO, or you may terminate the call 
	with the H command. Typing ATH will hang up the line 
	(bring it on-hook), bringing the modem out of the On-Line 
	state. So the command to hang up a call is three plus 
	signs and then ATH.

2.      DTR Control. If DTR (Data Terminal Ready) is turned off for 
	50 milliseconds or more, a disconnect will occur. This is 
	probably the most common method used by computer 
	systems at the automatic answer end of the line to 
	cause the answering modem to disconnect after log off 
	procedures.

3.      Loss of Carrier. After a data connection has been established,  
	the modem will disconnect if a loss of carrier occurs for 700   
	milliseconds (.7 seconds) or more. The 700 mSec 
	time can be configured for any time from 0 to 25.5 
	seconds, in 100 mSec increments, with S-
	Register S10. Note that one cause of carrier loss would be if 
	one of the modems were to disconnect normally. S10 
	works for speeds of 2400 bps or below, otherwise carrier        
	loss will take about 20 seconds in a V.32/V.32bis 
	connection. S10 has no affect at V.32/V.32bis speeds.

4.      Abort Timer. Answer Mode: When OH (Off Hook) comes on,  
	the called modem will start a 45 second timer and wait for a    
	carrier signal from the originating modem. If carrier 
	is not detected within this period, the modem will 
	disconnect (hang up) and be ready for another call. 
	Originate Mode: The abort timer will function the same as 
	in the answer mode, except that the timer will begin after the 
	modem has completed dialing, instead of when it first 
	goes off hook. It is possible to change this 45                 
	second wait-period to any other value from 1 second up to 254 
	seconds by reconfiguring S-Register S7 (see Chapter 4).

5.      Inactivity Timer. Causes the modem to disconnect if no data is 
	being transmitted or received for a certain period of 
	time. The timer is restored anytime a character is 
	passed through the serial port in either a send 
	or receive case. This function is controlled by S-
	Register S30. The inactivity timer can be disabled 
	by setting S30 to 0, which is the normal factory default,       
	or set to time out after the time selected by the state of S-   
	Register S30.


3.1     Introduction

The MT2834MR incorporates a microprocessor-based Command 
Mode, which allows you to use your computer keyboard or 
communications software to interact with your modem. When your 
modem is in Command mode, you have access to a complete 
communications system which allows you to use a number of features 
including the basic AT command set described in this chapter.  The 
basic AT command set allows you to type phone numbers for automatic 
dialing without a telephone set, configure various modem options and 
monitor phone activity.  Beyond the basic AT commands and 
capabilities, your modem can also perform advanced features such as 
error correction, data compression, speed conversion and more.  Some 
of those features are covered in Chapter 5 of this manual.
This chapter explains Command mode, and shows you how to use each 
of the basic AT commands.

The MT2834MR AT commands and responses are compatible with all 
systems and software that have been programmed for automatic, 
software-controlled autodialing using the standard AT command set.
The MT2834MR also provides V.42 error correction (using the MNP 
or LAP-M protocols), data compression (using the MNP) Class 5 and 
V.42bis protocol), speed conversion, and remote configuration. These 
advanced features are described in either Chapter 5 of this manual. 

3.2     Typographic Conventions Used in This Manual

It is important to point out the difference between the letter O and the 
number 0. Both of these characters will be used in the MT2834MR's 
commands. As you can see, the letter O is "fatter" than the number 0. 
We do not use the overstriken 0 to symbolize zero in this manual.
The Carriage Return and Control keys are used in many of the 
MT2834MR commands. Some keyboards label the Carriage Return key 
as ENTER, others use the word ENTER, and still others use an arrow 
pointing down and then left. The symbol <CR> is also commonly used. 
In this manual, we symbolize Carriage Return with the word ENTER, 
and will usually use the phrase "hit ENTER" to instruct you to press the 
Carriage Return key.

We symbolize the Control key with CTRL. For example, Control X, 
which is accomplished by pressing the X key while holding down the 
Control key, is written as CTRL-X.

3.3     Functional Modes

The MT2834MR can be in one of two functional modes. These are 
"Command mode," and "On-Line mode." (There is also an in-between 
mode, "Wait-For-Carrier," where the modem is out of Command mode 
but not yet really On-Line.) When the modem is initially powered up, it 
is in Command Mode, and is ready to accept commands from your 
keyboard or software, and respond to any Command Mode commands 
(described later).

The MT2834MR enters On-Line mode after dialing and making a 
connection with another modem, and then detecting a valid carrier 
signal tone. If no carrier signal is detected within a certain time, the 
modem abandons the call and re-enters Command mode.

Once On-Line, the modem exits On-Line mode if the carrier signal is 
lost or intentionally dropped. When this happens, the modem hangs up 
and re-enters Command mode.

The MT2834MR can exit the On-Line mode without losing the carrier 
signal. This is accomplished by typing certain "escape" characters while 
on-line, which brings the modem back into Command mode without 
terminating the connection.

The MT2834MR can also enter On-Line mode without going through 
the dialing process, by typing either the O command or the A command. 
This is explained later in this chapter, as are all of the MT2834MR's 
commands.

3.4     AT Commands

A variety of autodial operations and modem options are controlled 
when the MT2834MR is in Command Mode. This chapter covers each 
command in detail. There are also several option configurations stored 
in "S-Registers", which can be accessed in Command Mode (refer to 
Chapter 6). Error Correction commands are covered in Chapter 5 of this 
manual. 

The MT2834MR commands are listed below in alphabetical order in a 
format that will help you remember the command.
Modem Configuration - Command Letters

AT              ATtention code that precedes most commands
A               Answer mode
A/              Repeat Last Command
A:              Continuous redial until call answered*
&A              Answerback (proprietary feature)
$An             Auto-Reliable Buffering
#An             Auto Speed Select
$AS             IBM AS/400 Support
Bn              Bell or ITU-T answer tone select 
&Bn             Transmit Buffer size
&BSn            Maximum TX Block Size
$BAn            Baud Adjust
&Cn             Carrier Detect control
*C              Caller ID Detection (optional)
Ds              Dial
DsDn            Store Telephone Number
&Dn             DTR Control
$Dn             DTR Dialing
En              Echo Commands
$En             Enable/Disable Error Correction
%En             Escape Method
$EBn            Asynchronous Word Length
&En             Mode [normal, auto-reliable, or reliable]
&En             Flow control [None, CTS, or Xon/Xoff]
&En             Pass through XON/XOFF
&En             Enq/Ack pacing
&En             Normal mode flow control
&En             Pacing
&En             Data compression disable/enable
$F              Enable/Disable Auto-Reliable Fallback Character 
#F              Fallback modes when on-line
&F              Fetch Factory default values
$Fn             Enable/Disable Fallback character
#Gn             Guard tones*
H               Hook on/off control, or Hang up
$H              Help screens
I               Identify modem model/revision
#L              V.42 mode select (LAP-M/MNP)
L               List stored telephone numbers
L5              List current configuration parameters 
L6              List current S-Register Values
L7              List additional configuration parameters 
L8              List On-Line Diagnostics
&Ln             Lease line commands
$MI             MI/MIC Control*
Mn              Sync/Async control
$MBn            Modem Baud Rate
Nd              Dial Stored Telephone Number
NdNe            Number Linking  
O               On-line from Command Mode
P               Pulse Dial
&Pn             Set Pulse dial ratio*
#Pn             Parity Select
Qn              Result Codes
&Qn             Command set select
Rn              Reverse this mode
&Rn             CTS control
&RFn            CTS follow RTS control
$Rn             Retransmit count
S=              S-Register, set value
S?              S-Register, read value
$SBn            Serial port Baud rate
&Sn             DSR control
&SFn            DSR follow CD control
$SP             UNIX UUCP Spoofing
T               Tone dial
#T              Enable/Disable Trellis Coded Modulation 
&Tn             Recognise RDL signal
U               U-loop test
Vn              Verbose or Terse result codes
W               Wait for new dial tone
&Wn             Store configuration in RAM
X               Extended or basic Result Codes and Call Progress
&Xn             Clock select
Yn              Long space disconnect
Z               Zap (reset modem)
+++             Escape to Command Mode when on-line
,               Pause in dialing
;               Revert to Command Mode after dialing
!               Flash On-Hook
@               Quiet Answer
+++AT<CR>       Escape Sequence: Entering Command Mode 
		While On-Line
BREAK AT<CR>    Alternate Escape Sequence: Entering 
		Command Mode While On-Line

Refer to Appendix F of this manual for a summary of commands.

3.5     Result Codes

You can choose result codes that closely match those of the "Standard 
AT" command set ("Standard AT" Responses) or enhanced function 
result codes that have been used in Multi-Tech modems in the past 
("Multi-Tech responses"). The &Q command selects which result codes 
will be used.

The Command mode provides you with several responses, or "Result 
Codes," that can aid you in Command mode operation. These Result 
Codes are displayed on your monitor or printout.

You can choose to have these Result Codes displayed in a "verbose" 
format (complete words), or in a "terse" format (single digit numbers). 
The factory default setting is for the verbose format. To change this 
setting to the terse format, use the V command.

You can also choose basic result codes (connect with no speed 
indication), extended result codes (with speed indication), and whether 
you want call progress indications (busy and no dial tone) added to the 
extended result code set. This is controlled with the X command.

MT2834MR RESULT CODES

CODE            DESCRIPTION

OK              Your command was executed, and the     
		MT2834MR is ready for your next         
		command.

CONNECT         A carrier signal was detected at 300 bps.*

RING            A ring signal was detected from an incoming call.

NO CARRIER      No carrier signal was detected, or the carrier 
		signal was lost.

ERROR           An error is present in your command sequence, 
		(e.g., invalid character or too many characters).

CONNECT 1200    A carrier signal was detected at 1200 bps.*

NO DIALTONE**   No dial tone was detected, and your 
		modem will not dial.**

BUSY**          A busy signal at the number you 
		dialed was detected.**

NO ANSWER       The Remote system did not answer.

CONNECT 2400**  A carrier signal was detected at 2400 bps.*

CONNECT 4800    A carrier signal was detected at 4800 bps.*

CONNECT 9600    A carrier signal was detected at 
		9600 bps.*

CONNECT 14400   A carrier signal was detected at 14,400 bps.*

CONNECT 19200   A carrier signal was detected at 19,200 bps.*

CONNECT 21600   A carrier signal was detected at 21,600 bps.*

CONNECT 24000   A carrier signal was detected at 24,000 bps.*

CONNECT 26400   A carrier signal was detected at 26,400 bps.*

CONNECT 28800   A carrier signal was detected at 28,800 bps.*

CONNECT 1275    The modem is connected in V.23 mode.

*       These responses are used only in the Extended Result Code 
set, and the CONNECT response will indicate a bps connection. When 
the Basic Result Code set is used, the CONNECT response can mean 
either 2400, 4800, 9600, 14,400, 19,200, 21,600, 24,000, 26,400, or 
28,800 bps. A connection using error correction will be indicated by the 
addition of the word LAP-M or RELIABLE (verbose) or the letter L or 
R (terse) to the CONNECT responses. A connection using MNP5 data 
compression will be indicated by the addition of the word 
COMPRESSED (verbose) or the letter C (terse) to the CONNECT 
responses.

**  In the modem's default setting of blind dialing, these responses will 
not be used.

3.6     Command Mode Fundamentals

This section discusses Command Mode fundamentals, Dialing 
commands, Immediate Action commands (except dialing), and 
Configuration commands. The rest of the commands are covered in 
Chapter 5.

3.6.1   Entering and Executing Commands

When you type commands for the MT2834MR, each command must 
start with the Attention Characters AT.  Attention characters can be 
typed in either upper case (capital) or lower case (small) letters.
The AT characters alert the modem that a command follows. The 
Attention command can also be used to clear the command buffer, by 
typing AT and then hitting ENTER.

Typing the AT characters automatically sets the modem's speed to 
match the speed of your computer or terminal, and also sets the 
modem's parity.

The MT2834MR will not execute a command until you hit ENTER. 
Therefore, ENTER should be pressed when the entire command has 
been typed. There are some exceptions to this rule. The A/ (Repeat Last 
Command) command is executed without hitting ENTER. The A: 
command is also executed without hitting ENTER.

Typing A/ will cause the MT2834MR to repeat the last command that 
was executed. This last command remains stored in the modem's 
command buffer until the Attention Command AT is typed. Therefore, 
AT must not be typed before A/ is typed. The A/ command will have no 
effect if there is no command stored in the command buffer. It is not 
necessary to hit ENTER to execute this command.

Many MT2834MR commands consist of a letter, followed by a number 
(0, 1, etc.). If a command like this is typed without the number, the 
modem will assume that its value is zero (0). For example, if you type 
ATH as a command without a 0 or 1 following the H, the command will 
be ATH0. (In this example, the effect is that the modem hangs up.) As 
you become more familiar with the MT2834MR's commands, you will 
find yourself taking advantage of this shortcut.

3.6.2   Command Editing

You can use the BACKSPACE key on your keyboard to edit characters 
in the command line. The command will not be executed until you hit 
ENTER. The BACKSPACE key erases the previous character for 
retyping.

The BACKSPACE key will not erase the AT characters once they are 
typed. If your keyboard has no BACKSPACE key, CTRL-H will 
accomplish the same thing. The character recognized by the modem as 
BACKSPACE may be changed to any other ASCII character with S-
Register S5.

To cancel an entire command that has been typed but not yet executed, 
type CTRL-X. This also clears the command buffer. The effect is the 
same as backspacing to cancel the entire command, only quicker.
Characters typed in a command are stored in the MT2834MR's 
Command Buffer (memory) until executed by hitting ENTER. The 
Command Buffer's capacity is sixty characters. The Attention 
Characters AT do not count in the sixty allowed Command characters. 
Spaces, which may be used for increased display readability, may be 
used when typing a Command, but are not stored in the Command 
Buffer and are not counted in the sixty allowed characters. Hyphens, 
parentheses etc., are not allowed.

If the sixty character limit is exceeded or if invalid characters are typed, 
the Command Buffer is automatically erased, and an ERROR message 
appears. You then retype the command within the sixty-character 
maximum, using only the allowed characters.

Note: In some applications, such as auto-answer only, you may disable 
the Command mode altogether. When you do this, the MT2834MR 
ignores all commands, and functions as an auto-answer non-intelligent 
modem. This is done with DIP-Switch #8 on the modem card 
(explained in Chapter 7). The factory default setting is Command mode 
enabled.

3.7     Dialing Commands

3.7.1   Dialing Action Commands

D       Dial Command

The letter D in a command causes the MT2834MR to dial the telephone 
number immediately following it. For example, if you type  
ATD5551212 and hit ENTER, the MT2834MR dials the number 555-
1212.

The D command is also used in conjunction with a telephone set for 
manual dialing. You dial the number on your telephone set, and after 
hearing the answer tone on your handset, type ATD on your keyboard 
and hit ENTER. Then hang up the handset. Unless you have a specific 
need to dial in this manner, we recommend you use the first method, 
where you type the telephone number on your keyboard.

The MT2834MR gives you several choices regarding dialing methods. 
You can use tone or pulse dialing, by inserting a letter T or a letter P in 
the command string. (See Section 3.7.2 on Dial Modifiers).
You can also configure the modem to either wait for and detect dial 
tones and busy signals (which we call "Wait-for-Dial-Tone" dialing or 
"Smart" dialing), or work with timed pauses without dial tone and busy 
signal detection (which we call "Blind" dialing). (See Section 3.9 X 
Command.)

Note: There is another method of dialing, called "DTR Dialing", where 
by manipulating the DTR signal on pin 20 of the RS232C interface, a 
number stored in the modem's memory is automatically dialed. See 
Section 3.9 on DTR Dialing ($D command) for details.

A:      Continuous Redial (not used in MT2834MRK or 
MT2834MRI)

If you select the Wait-For-Dial-tone method of dialing (see X3 or X4 
command), it is possible for you to command the MT2834MR to 
continuously redial (maximum 10 redials for DOC units) a busy number 
until your call is answered. This is done with the A: command.
This command is used only if you have already reached a busy number 
after executing a normal dial command. Type A: (you need not type 
AT, nor do you need to hit ENTER), and the modem redials the 
number. If you again reach a busy signal, it redials again and again until 
it no longer detects a busy signal. To stop the redialing, press any key.

:               Continuous Redial

Another way to redial a phone number continuously is to type a colon(:) 
at the end of the phone number. The result is the same as if you had 
typed A: after observing that the number was busy on the first dialing 
attempt. Using the colon in the dial command is a step saver.

H       Hanging Up, and Bringing the Phone Line Off Hook

You can make the MT2834MR hang up (go On Hook), or go Off Hook, 
with the H command. Type ATH1 to bring the line Off Hook, just as if 
you had picked up the telephone handset.

To hang up, type ATH0 or ATH (remember that the default value is 0 
when no number is typed).

It is not necessary to type H1 to bring the line Off Hook when using the 
D command to dial, since the modem will go off hook automatically 
when you hit ENTER at the end of the dial command.

3.7.2   Dial Modifiers

There are several commands that can be included within a dialing 
command (following the letter D), called "dial Modifiers". They have 
various functions, including the selection of Pulse or Tone dialing, 
pauses in the dial sequence, automatic redials if a number is busy, and 
reverting to Command mode or switching to Answer mode after dialing.

P, T    Pulse or Tone Dialing

The MT2834MR can dial numbers using either pulse or tone dialing, or 
a combination of both methods. Pulse dialing is the method used by 
rotary-dial telephones, which involves the timed opening and closing of 
a line relay. Tone dialing is that used by pushbutton Touch-Tone 
telephones, and is sometimes referred to as DTMF, or Dual-Tone 
Multi-Frequency dialing.

The dialing method is controlled by typing a P for Pulse or a T for Tone 
in the dialing command, right before the digits you wish to have dialed 
in that manner.

For example, to pulse-dial the number 555-1212, type ATDP5551212 
and hit ENTER. To tone-dial the same number, type ATDT5551212 
and hit ENTER.

If neither Pulse nor Tone dialing is specified in the dial command, the 
MT2834MR uses whatever method was last used. If the modem has 
been reset or was just powered up, it uses Pulse dialing, even if you do 
not include the letter P in your dial command.

Nearly all telephone systems in the U.S. are compatible with tone 
dialing. Since that is the faster method, you will probably use tone 
dialing.

An example of combining pulse and tone dialing could involve a PBX 
system where 9 has to be pulse-dialed first, then the rest of the number 
tone-dialed after pausing for a second dial tone. To dial the number, 
type ATDP9, T5551212 and hit ENTER. (The comma causes a pause, 
which is explained soon.)

&P      Set Pulse Dial Ratios

The &P command sets the time ratios between the open and closed 
positions of the dialing pulse frequencies. To set a dialing pulse ratio of 
60mSec to 40 mSec, type AT&P0. To set a ratio of 67 mSec to 33 
mSec, type AT&P1. The factory default setting is &P0.

The &P command is not available on the MT2834MRK. 

,       Automatic Pauses in Dialing

You can cause the MT2834MR to pause during the dialing sequence by 
typing a comma character where the pause is desired. This pause lasts 
two seconds (4.8 seconds on the MT2834MRK). If a longer pause is 
desired, more than one comma may be typed consecutively, with each 
one causing a two second pause.  You can also change the length of the 
pause caused by the comma from 0 up to 255 seconds with S-Register 
S8 (refer to Chapter 4).

Each comma used in a dialing command does count as one of the sixty 
allowed characters. 

Y       Long Space Disconnect

The Y command enables or disables the modem's ability to respond to a 
long space disconnect condition. The command Y0 disables it (factory 
default setting) and Y1 enables it.

W       Wait for New Dial-Tone

A W inserted in the dialing command causes the MT2834MR to wait 
for another dial tone, and the modem will not resume dialing until 
another dial tone is detected.

It is not necessary to type a W at the beginning of the dialing command 
to wait for a modem dial tone, since the modem will pause 
automatically.

In order for this command to work, you must first select Wait-for-Dial-
Tone dialing with the X2 or X4 command, so that your modem can 
detect the dial tone.

;       Returning to Command Mode After Dial Command Execution

A semicolon (;), when typed as the last character of a dialing command, 
causes the MT2834MR to return to Command mode immediately after 
executing the command instead of waiting for a carrier signal and going 
on-line.

For example, type ATDT5551212; to simply tone-dial the number, and 
do nothing afterwards except go back into Command mode. This is 
useful in dialing applications where modem data transfer is not desired, 
such as voice communications, or in applications involving the use of 
Touch Tones as a data entry method, such as bank-by-phone.

R       Reversing the Mode of Operation

In certain applications you may need to reverse the modem's mode of 
operation from originate to answer, or answer to originate, so that it 
answers the phone and goes into originate mode, or dials a number and 
goes into answer mode. This command turns off the reversing function 
with the R0 command and turn it on with the R1 command.

!       Flashing On Hook

Some switchboard systems react to a momentary On Hook. An 
exclamation mark inserted in the dialing command causes the modem to 
"flash" on hook for a half second, just as if you had held the switch 
hook on a telephone set down for a half second. (The flash is 90 mSec. 
on the MT2834MRK.)

For example, to flash On Hook after dialing the number 555-1234 in 
order to transfer to Extension -5678, type ATDT5551234,,!5678. The 
commas cause a 4 second pause (just to be safe).

@       Quiet Answer

The @ command causes the MT2834MR to wait before processing the 
next symbol in the dialing string. The wait is for one or more ringbacks, 
followed by 5 seconds of silence. If the time (specified by S-Register 
S7) passes before the rings and silence, a NO ANSWER (R) result code 
is processed. The @ command is used for accessing a system that does 
not provide a dial tone.

For example, ATDT5551212@7853500 causes the MT2834MR to dial 
the first number (555-1212) and wait for the time specified in S-
Register S7 for at least one ringback and 5 seconds of silence. If a busy 
signal is detected, the MT2834MR hangs up and generates a BUSY 
result code. If it does not detect 5 seconds of silence, a NO ANSWER 
result code is generated after hanging up. If 5 seconds of silence is then 
detected, 785-3500 is dialed.

3.7.3   Phone Number Memory Commands

D...N   Storing Phone Numbers

A telephone number and command line of up to sixty characters may be 
stored in the MT2834MR number memory. As many as ten of these 
numbers may be stored. Each number is given a name, using the codes 
N0 to N9.

To store a phone number, type ATD, then the number as it would be 
dialed along with any P, T, R, ; or , characters, and then type N  
followed by the phone number's "name," (any number from 0 through 
9) and then hit ENTER.

For example to store the number 1-612-631-3550 as number N3, type 
ATDT16126313550N3 and hit ENTER. The number is not dialed with 
this store command.

After storing a phone number, check if it has been stored correctly by 
typing ATL and hitting ENTER. 

When phone numbers are stored, the entire command line is also stored 
so that you can effectively create a macro for each number. For 
example, if you know a particular number needs extended result codes, 
detect busy/dial tone, error correction, Xon/Xoff flow control, pacing, 
and data compression, type: 

ATX4&E1&E5&E13&E15DT16126313550N3.

N       Dialing a Stored Number      

To automatically dial a telephone number that you a have stored in the 
MT2834MR number memory, type ATNn (where n = 0 through 9). For 
example, to dial a number stored at N3, type ATN3 and hit ENTER. Do 
not include the letter D in this command, or the stored number is erased. 

NN      Number Linking

You may cause the MT2834MR to dial a second number automatically 
if the first number you dialed is busy. This is useful in a situation where 
a computer can be accessed through more than one phone number. This 
is called "linking".

To link the number at N1 to the number at N2, type ATN1N2 and hit 
ENTER. Several numbers can be linked in the same command. For 
example, to link N1 to N2 to N3 to N4, or link N1 to N2 and back to 
N1 and then back to N2, type ATN1N2N3N4 in the first example, and 
ATN1N2N1N2 in the second example. 

The only limit to the number of numbers that can be linked is the 60 
characters allowed in a command line. Number linking can not be used 
with blind dialing, since busy signals would not be detected. You would 
have to select the Wait-for-Dial-Tone dialing method using the X 
command to use the Number Linking feature.

Note: The NN command is not used in the MT2834MRK.

L       Listing Numbers Stored in Memory

Telephone numbers stored in the MT2834MR's memory may be listed 
and displayed with the L command. It displays all ten stored numbers in 
a format like that shown below. All digits and command letters are 
shown. The number's "name" (0 thru 9) is shown first, followed by the 
complete dialing command and telephone number as originally typed.

Type ATL and hit ENTER to display these numbers on your video 
screen or printout. An example of an L command listing is shown 
below.
		
		0 T14082345678
		1 T16125551212;
		2 P9, T14089876543
		3 T3738315,12101,16126313550
		4 T6313551R
		5
		6 P9,4258513
		7
		8 ATX4&E1E5&E13&E15DT16126313550N3
		9 T12138880123

3.8     Immediate Action Commands

$H      Help Screens

The $H command gives you short explanations on how to use each 
MT2834MR command. The $H command can be quite useful if your 
manual is not handy and you are in the middle of a communications 
session. Although the explanations are quite abbreviated compared to 
those in this manual, they should prove to be helpful reminders when 
needed.

At the time of this writing, we have three screens of Help information 
(Screen #1, #2 and #3), and more screens may be added in the future. 
The Help commands are structured so that you can call up one of three 
Help screens, as follows:

AT$H1 = Help Screen #1
AT$H2 = Help Screen #2
AT$H3 = Help Screen #3

+++AT<CR>       Escape Sequences -- Entering Command Mode        
		While Still On-Line

It is possible to cause the MT2834MR to enter the Command mode 
after the modem has gone on-line with a remote modem, without 
disconnecting the call. This is accomplished by typing an Escape Code. 
The default Escape Code used by the MT2834MR is three plus signs 
(+++) followed by the letters A and T, up to sixty command characters 
(most typically H, to hang up), and an ENTER. The number of 
command characters allowed after +++AT<CR>, is defined by S-
Register S34. S-Register S34 defaults to ten command characters. 

When this is done, the modem will escape to Command mode, execute 
the command (if any), and then remain in Command mode. For 
example, to hang up the modem at the end of a call, the command 
would be +++ATH followed by ENTER. There is no need to 
incorporate pauses before and after the plus signs, as done in earlier 
modems.

BREAK AT<CR>

The MT2834MR provides an alternative Escape method, using a Break 
signal as the Escape Code. The Break signal allows the start-stop DTE 
(data terminal equipment) to signal the modem without loss of character 
transparency. With this method, a BREAK signal is used instead of the 
three plus signs. The BREAK is followed by the letters A and T, up to 
60 command characters, and ENTER. When this is done, the modem 
will execute that command, but remain in the normal On-Line mode 
unless the command was to hang up and/or reset the modem (an H or 
Z), in which case the modem would be in the Command mode after 
executing that command.

* Readers interested in further information on the use of BREAK signals 
as escape codes may wish to consult the ITU-T X.28 Recommendation. 
In the "Provisional Recommendation X.28 (Geneva 1977)", 
information on the topic can be found in Section 4.9, entitled "Escape 
from the data transfer state". More recent editions have been published 
in 1980, 1984 and 1988. ITU-T publications can be obtained from 
Omnicom, Inc., 112 Park Street SE, Vienna, VA 22180, Phone 
703/281-1135, FAX 703/281-1505.

%E      Escape Sequence Options -- Entering Command Mode While 
On-Line

As mentioned, the default setting is for the modem to respond to the 
+++ escape method. Optional settings are for the modem to respond to 
the BREAK method, for the modem to respond to either the +++ or the 
BREAK Methods, and for the modem to ignore both methods and not 
escape. The %E command is used to select these options, as follows:

%E0   =       Modem Won't Escape
%E1   =       +++AT<CR> Method (factory default setting)
%E2   =       BREAK Method
%E3   =       Either +++ or BREAK Methods
%E4   =       Disable OK response to +++                
%E5   =       Enable OK response to +++

Note: The Escape Code for Remote Configuration (see Appendix K) 
has %%%AT<CR> for the factory default setting.

O       Exiting Command Mode, Going Back On-Line

To bring the MT2834MR out of Command mode back into On-Line 
mode, type ATO (where O is the letter O, not the number 0). In this 
case, the O command reverses what was done by typing the Escape 
Code. The O command places the modem in the same On-Line mode 
(Originate or Answer) that it was in prior to going into Command mode.

A       Forcing Answer Mode

With the A command you can force the MT2834MR into the Answer 
mode. Type ATA Mode when in Command mode to immediately bring 
your modem off-hook, out of Command mode and into the On-Line 
Answer mode, and cause it to transmit its carrier signal over the phone 
line. If no responding carrier tone is received by your modem within 45 
seconds (or some other time as determined by S-Register S7), your 
modem will cease transmitting its tone, hang up, and go back into 
Command mode.

I       Inquiry for Product Code

Some systems or software packages automatically check the 
"Identification" of the modem with which they are communicating, by 
using the I command. This "read" command lets the software determine 
the type of modem with which it is communicating.
When ATI or ATI0 is typed, the MT2834MR responds with 247. When 
ATI1 is typed, the modem responds with a three-digit firmware version 
number. 

L5, L7  Listing Current Operating Parameters

The L5 and L7 commands allow you to list the current operating 
parameters of your modem. This information can be very useful when 
reconfiguring your modem, such as when you are changing 
communications software or when you are changing your factory 
default settings.

To list the MT2834MR's current operating parameters, type ATL5 for 
the basic parameters. Type ATL7 to list additional parameters. The 
parameters for all of the configuration commands (covered in section 
5.9) are listed.

L6      Listing S-Register Values

The L6 command lists the current values stored in the modem's S-
Register. This information can be very useful if you wish to change S-
Register values. (Refer to Chapter 4 for more information on S-
Registers.)

L8      Listing On-Line Diagnostics

The L8 command displays the current on-line CONNECT status of the 
MT2834MR.  This display can be printed and used as a modem status 
report or as diagnostic information (such as when calling Tech 
Support).  This report is given only when on-line.  To activate this 
command type +++AT<CR> (on-line escape command while 
maintaining command mode), then type ATL8.  Your modem's current 
on-line condition (e.g., Link Type, Line Speed, Serial Speed, Type of 
Error Correction/Data Compression, Number of past Retrains, etc.) is 
displayed.

3.9     Configuration Commands

3.9.1   Configuration Storage and Default Commands

&F      Loading Factory Defaults

Because the modem has the capability of storing reconfigured 
parameters and S-Register values into its non-volatile Random Access 
Memory (RAM), you may wish to have a choice between these RAM 
stored parameters and values or the factory default parameters and 
values (as determined by the modem's ROM and      DIP-Switches). The 
&F command lets you set the modem to the factory defaults in ROM. 
The modem will then ignore the parameters and values that remain 
stored in RAM.

The command AT&F causes the MT2834MR to use the factory default 
setting ROM configuration parameters and S-Registers values. To 
replace the parameters and values stored in RAM with all factory 
default settings, combine the &F and &W commands by typing 
AT&F&W and hitting ENTER.

The &F8 and &F9 commands determine the function of the &F 
command.

If you type the &F8 command (the factory default setting), and later 
type a subsequent &F command, the modem reads the factory default 
settings, regardless of what is stored in non-volatile RAM (defined by 
the &W command).

If you type the &F9 command, and then type a subsequent &F 
command, the modem reads the parameters and values stored in non-
volatile RAM as the defaults. The result is that the setting of the &W 
command defines the source of the default parameters and values that 
your modem reads as its factory default settings.

&W      Storing Configuration & S-Register Parameters in the 
Modem's Non-Volatile Memory

The MT2834MR can store its configuration parameters and S-Register 
values in its non-volatile read/write (RAM) memory.

Type the &W command to store parameters and S-Register values in 
the modem's RAM, and to prevent any reconfiguration from being lost 
on a power-down or Reset (ATZ) condition. 

Type AT&W0 (or AT&W) to cause the modem to store its current 
parameters and values in its non-volatile RAM. This command also sets 
the modem so that when it is powered up, or when it is reset with the 
ATZ command, the modem will read all of its configuration and S-
Register parameters from RAM, and not from the factory default setting 
in ROM.

Type AT&W1 to set the modem so that it does not store its parameters 
to RAM, and, when a subsequent power on condition or ATZ command 
is executed, parameters will be read from the factory default settings in 
ROM and from the DIP-Switch settings.

Z       Modem Reset

Type the Z command to reset all MT2834MR configurations to their 
factory default settings, and to clear the Command mode buffer. When 
you type ATZ, the result is the same as if you had disconnected, and 
then reconnected power to the modem. When the ATZ command is 
executed, the state of the &W command determines where the default 
values originate. (&W0 defaults come from RAM and &W1 defaults 
come from ROM.)

3.9.2   Command/Response

E       Echoing Command Mode Characters

If the MT2834MR is connected to a full-duplex terminal or computer, 
you may have to configure the modem to echo back characters typed 
while in Command mode in order for them to be displayed. The E 
command is used to configure the Command mode echo, with ATE0 
disabling the echo and ATE1 enabling the echo.

Q       Result Codes (Enable or Disable) and No Response Answer

The Q command enables or disables Result Codes and the No Response 
Answer mode of operation.

Regarding Result Code Enable/Disable, you may want to disable the 
Result Codes altogether in certain applications, such as computer-
controlled autodialing. The command ATQ1 disables Result Code 
transmissions and ATQ0 (or ATQ) enables them. In typical operation, 
the originate mode and answer mode are "intelligent" operations, 
controlled by the position of the modem DIP-Switches and previously 
executed commands.

Regarding No Response Answer, you may want Answer mode handled 
without responses, and echo turned off but want Originate mode still 
intelligent. This is called the No Response Answer mode. ATQ2 selects 
the No Response Answer mode. If you do not select any mode, the 
factory default setting enables the Result Codes to be sent.

&Q      Result Codes - "Multi-Tech" or "Standard"

The MT2834MR modems give you a choice between Multi-Tech 
responses (which include RELIABLE and COMPRESSED responses), 
and a set that more closely matches the Standard AT command set 
result codes.

AT&Q0 selects Multi-Tech responses with Reliable/Compression 
modifiers, DIALTONE/BUSY/NO ANSWER. With this setting, the 
terse response for CONNECT 2400 is 9. This is the factory default 
setting.

AT&Q1 selects Standard AT responses with no Reliable/Compression 
modifier. With this setting, the terse response for CONNECT 2400 is 
10.

Refer to Appendix D for a summary of Result Codes.

V       Result Codes - Word or Digit

The V command controls whether the MT2834MR's result codes are 
displayed as words ("verbose") or single digits ("terse").

For example, if after dialing, no carrier signal is detected, the result can 
be displayed either as NO CARRIER, or as the digit 3.

Type ATV0 (or ATV) to cause the MT2834MR to display the Result 
Codes as digits. Type ATV1 to display the Result Codes as words. If 
you do not select a method, the factory default setting will cause the 
modem to use verbose results.

X       Result Codes (Basic or Extended) and Call Progress Method

The X command selects both the dialing method ("dumb" or "smart"), 
as well as various response combinations related to the dialing method 
selected.

Regarding result code selection, you can choose to have certain 
responses suppressed, and whether or not you want speed indications 
along with the CONNECT responses. 

The MT2834MR provides "Basic" and "Extended" Result Code sets. 
The difference between the two is the Basic set provides one response 
(CONNECT) to indicate a connection, while the Extended set provides 
several responses (CONNECT, CONNECT 1200, CONNECT 2400 
and CONNECT 9600).

Regarding the method of dialing, the MT2834MR can detect standard 
dial tones and busy signals. This capability ("smart dialing") allows the 
modem to wait for a dial tone, and when one is detected, to begin 
dialing immediately.

The MT2834MR also can detect a distant busy signal if after dialing, it 
reaches a busy number. This is useful because it allows the modem to 
immediately abandon a call, rather than wait 45 seconds for a carrier 
signal that will never come.

The MT2834MR gives you a choice between the wait-for-dial-tone 
("smart") dialing method we just described, and blind ("dumb") dialing, 
where instead of detecting actual dial tones, the modem relies on timed 
pauses. When the wait-for-dial-tone method is chosen, the busy signal 
detection capability is also activated. The X command is also used to 
select which dialing method is used.

Five different X commands are available (X0 through X4), with five 
different effects on the MT2834MR's result code set.

X0      Provides the basic (short) result codes and             
	provides "dumb dial" capabilities.

X1      Provides the extended result codes and provides                 
	"dumb dial" capabilities.

The remaining X commands select "smart" dialing methods and turn on 
extended result codes.

X2      Looks for dial tone only and will not provide a busy            
	response.

X3      Looks for busy only and not for dial tone.

X4      Looks for dial tone and for busy.

The factory default setting is X4, which selects extended and "smart" 
result codes.

3.9.3   RS232 Interface Commands

&C      Carrier Detect Control 

The &C command lets you control the status of the Carrier Detect 
signal (CD - Pin 8) on the RS232C interface. You have three choices. 
You can force the signal high, allow it to act normally, or set it up so 
that it will stay high until the modem disconnects, go low momentarily, 
and then go high again. The last option is useful with some CBX phone 
systems and mainframe front ends, which require CD to act in this 
manner.

To allow CD to act normally, type the command AT&C1 (this is the 
factory default setting). To force CD on, type the command AT&C0. 
To set up CD so that it drops for one second on disconnect and then 
comes up again, type AT&C2. (If you want the drop time to be 
something other than one second, use S-Register S24 to change this 
value. Refer to Chapter 4 for S24 instructions.)

&D      Data Terminal Ready Control

Data Terminal Ready (DTR) on pin 20 of the RS232C interface is 
required for the MT2834MR to operate. A high DTR signal tells the 
modem that the device to which it is connected is active, or "ready" to 
communicate through the modem. If the signal is not being provided on 
the RS232C interface, 12-position DIP-Switch #1 can be used to force 
the DTR signal on.

DTR can also be used to trigger a dialing sequence, called DTR 
Dialing. The condition of DTR can also be used to cause the modem to 
reset to its default parameters, just as if you had given the modem an 
ATZ command. To do this, type the command AT&D3 and hit ENTER. 
The modem will now reset itself whenever DTR is dropped from On to 
Off, and will also go on-hook (hang up) if it is on-line.

Type AT&D0 or AT&D to cause the MT2834MR to ignore DTR. Type 
AT&D1 to cause the modem to go on hook (hang up) with loss of DTR. 
The modem enters Command mode when DTR goes high again. Auto-
answer is disabled while DTR is low. Type AT&D2 to cause the 
modem to go on hook with loss of DTR. The modem enters Command 
mode when DTR goes high again.

&R      Clear to Send Control

The &R command lets you control the status of the Clear to Send signal 
(CTS - Pin 5) on the RS232C interface. You have three choices. You 
can force the signal high, allow it to act normally, or set it up so that it 
will stay high until the modem disconnects, go low momentarily, and 
then go high again. The last option is useful with some CBX phone 
systems and mainframe front ends, which require CTS to act in this 
manner.

To allow CTS to act normally, type AT&R0. To force CTS on, type 
AT&R1 (when the modem goes on-line, CTS still provides flow 
control). Type AT&R2 to set up CTS so that it drops for one second on 
disconnect and then comes up again. (If you want the drop time to be 
something other than one second, use S-Register S24 to change this 
value. Refer to the Chapter 4 instructions for S24.)
If you type the &R2 command, be sure that the CTS DIP-Switch on the 
modem circuit board is set to allow CTS to act independently of 
Request to Send (RTS). (Refer to Chapter 7 for details.) 

&RF     CTS/RTS Interaction Conrol

In typical operation, Clear to Send will follow Request to Send when 
the modem is on-line. In other words, if RTS goes off, CTS goes off in 
response. The &RF0 command enables CTS to follow RTS. In some 
applications, however, it may be necessary for CTS to operate 
independent of RTS. &RF1 allows CTS to operate independently 
regardless of the state of RTS. Refer to the &R command for control of 
Clear to Send functionality. The factory default setting is &RF1.

&S      Data Set Ready Control

The &S command lets you control the status of the Data Set Ready 
signal (DSR - Pin 6) on the RS232C interface. You have three choices. 
You can force the signal high, allow it to act normally, or set it up so 
that it will stay high until the modem disconnects, go low momentarily, 
and then go high again. The last option is useful with some CBX phone 
systems and mainframe front ends, which require DSR to act in this 
manner.

To allow DSR to act normally, type AT&S1 (this is the factory default 
setting). To force DSR on, type AT&S0. To set up DSR so that it drops 
for one second on disconnect and then comes up again, type AT&S2. 
(If you want the drop time to be something other than one second, use 
S-Register S24 to change this value. Refer to Chapter 4 instructions for 
S24.)

If you type the &S2 command, be sure that the DSR DIP-Switch on the 
modem circuit board is set to allow DSR to act independently of Carrier 
Detect (CD). Refer to Chapter 7 for details.

&SF     DSR/CD Interaction Control

In typical applications, Data Set Ready (DSR) will follow Carrier 
Detect (CD). &SF0 enables DSR to follow CD, and is the factory 
default setting. &SF1 enables DSR to operate indepent of CD. If this is 
the case, refer to the &S command for control of Data Set Ready 
functionality.

3.9.4   Phone Line Conditioning Commands

#A      Auto Speed Detect

The #A command lets you select operation as either a 9600/4800 bps 
ITU-T V.32 standard modem, a 2400 bps ITU-T V.22 bis (Bell 2400) 
standard modem, a ITU-T V.22/Bell 212A (1200 bps) modem or a Bell 
103/113 (300 bps) modem. The function of the #A command is to 
detect and select the operational baud rates which the MT2834MR will 
use for initial handshake and speed selection.

Note: The #A command does not control the originating bps rate of the 
modem (that is done by the Modem Baud Rate command $MBXXXX), 
but only answer mode fallback speeds.

Type AT#A0 (or AT#A) to cause the MT2834MR to operate starting at 
28,800 bps with fallback to 19,200 to 14,400 to 9600 to 4800 to 2400 
to 1200 to 300 bps. AT#A1 uses 28,800 bps only. The AT#A2 causes 
the modem to operate at starting speeds of 28,800 bps, with incremental 
fallback to 19,200, 14,400, 9600, and 4800 bps. The AT#A3 command 
causes the modem to begin operation as a V.22bis modem at 2400 with 
fallback to 1200 to 300 bps. AT#A1 is the factory default setting.

&L      Leased Line (2/4 wire, Answer/Originate) Mode Select

The &L command lets you select one of four modes of MT2834MR 
leased-line operation. You can select any combination of 2- or 4-wire 
operation in Answer mode or Originate mode. The factory default 
setting (on power up) is &L0 (dial-up mode operation).

Type AT&L1 to allow just one attempt at a leased line connection. 

Type AT&L2A for 2-wire operation in Answer mode. Type AT&L4A 
for 4-wire Answer mode operation. Type AT&L2D for 2-wire Originate 
mode operation. Type AT&L4D for 4-wire Originate mode operation. 

Note: You must include the A or the D command in the dialing string 
with the &L command.

The &L command is intended for use by the MultiModemManager 
administrator. MT2834MR power must be cycled to clear the &L 
command. The &L command is not stored in modem memory. DIP-
Switch #10 in the UP position (Dial-Up Operation) overides the &L 
command (refer to Chapter 7 of this manual).

B       Bell or ITU-T Tone

You can use the B command to select the frequency that the modem 
uses for its answer tone. (The answer tone is the tone transmitted by a 
modem receiving a call to the modem that called it, which initiates the 
handshaking between the two modems.) At higher speeds (2400 to 
14.4k bps) there is no conflict, because all use ITU-T frequencies. At 
lower speeds (0-1200 bps), in the U.S., some modems use the Bell 
frequency of 2225 Hz. However, the ITU-T specification for V.22bis 
has an answer tone frequency of 2100 Hz.

The ATB0 command enables the ITU-T answer tone. The ATB1 
command enables the Bell answer tone. The factory default setting is 
ATB0 (ITU-T tones). 

This B command is not available on the MT2834MRK.

$D      DTR Dialing

An alternate way to cause the MT2834MR to automatically dial is 
"DTR Dialing". The Data Terminal Ready (DTR) signal comes into the 
modem from the attached terminal or computer, on pin 20 of the RS232 
interface. With DTR dialing, the modem automatically dials a stored 
number as soon as it receives a high DTR signal. The DTR dialing 
method is popular when using the MT2834MR in synchronous 
applications.

To enable DTR Dialing, type AT$D1 and hit ENTER. The modem will 
dial the phone number you have stored at N0 when it receives a high 
DTR signal (see Section 3.7.3). DTR must remain high for the duration 
of the call (until disconnect). To disable DTR dialing, type AT$D0 (or 
AT$D) and hit ENTER.

When you use DTR Dialing, be sure that 12-Position DIP-Switch #1 is 
in the UP position, so that DTR is not forced on. (Refer to Chapter 7.)

#F      Fallback Modes When On-Line

If the line conditions deteriorate, the MT2834MR automatically drops 
its transmission speed (fallback).  The #F command controls the 
different ways that the MT2834MR falls back.  During operation, if the 
error rate becomes too great, the modem performs a retrain.  If after the 
retrain the error rate is still too high for 28,800 bps operation, the 
modem initiates a retrain at 4800 bps.

If after the first retrain the modem returns on-line at 28,800 bps, the 
modem starts a counter and a timer. If three retrains occur within a two 
minute period, the modem falls back to 4800 bps.

Type AT#F0 (or AT#F) will cause no fallback when on-line. Type 
AT#F1 to cause the MT2834MR to fall back (based on the error rate or 
if three retrains have occurred within a two minute period) from 28,800 
to 26,400 to 24,000 to 21,600 to 19,200 to 16,800 to 14,400 to 12,000 
to 9600 to 4800 bps.  The AT#F2 command enables incremental 
fallback from 28,800 bps to 4800 bps, but also enables fall forward 
(from 4800 bps to 28,800 bps incrementally) if the phone line 
improves.  AT#F2 if the factory default setting.

&G      Guard Tones

You can use the &G command to control the presence or absence of 
guard tones from the transmitter when in Answer mode, at either 1200 
or 2400 bps. Guard tones are used in Europe and other areas, in order 
for the modem to function in the telephone systems. Guard tones are not 
used in the United States.

AT&G0 turns off the guard tones, and is the factory default setting. 
AT&G1 turns on a 550 Hz guard tone. AT&G2 turns on an 1800 Hz 
guard tone. 

The &G command is not used on MT2834MRK units.

$MI     MI/MIC Control

The $MI command enables and disables the mode indicate/mode 
indicate common interface function. AT$MI1 enables MI/MIC 
operation and AT$MI0 disables it.

With the MI/MIC option enabled, the modem's A and A1 telephone line 
interface output leads are replaced with MI and MIC input leads. (Tip 
and Ring remain unaffected.) When MI and MIC are connected 
together, the modem goes Off Hook in Originate mode, for a time 
period specified by the modem's Abort Timer (S-Register S7). For 
example, a 45 second Abort Timer means that if the modem does not 
detect a carrier tone within 45 seconds after it goes Off Hook, it will 
disconnect. 

The $MI command is not available on the MT2834MRK.

NOTE: This option is a hardware modification that must be ordered 
separately; it is not automatically included with the MT2834MR 
modems.

&T      Enable or Disable Recognition of Remote Digital Loop Signal

The MT2834MR has several test features, which are covered in detail 
in Chapter 6. The tests are activated with different U commands, such 
as ATU0, ATU1 and so forth. There is one command, however, that is 
really a configuration command, so we will cover it here. That is the 
&T command, which enables or disables the modem's ability to 
recognize the Remote Digital Loop (RDL) test signal.

The command AT&T4 allows the MT2834MR to respond to a RDL 
signal, and place itself in digital loop. The command AT&T5 disables 
this capability, meaning that the modem will ignore the RDL signal. 
(Refer to Chapter 6.)

#T      Enable/Disable Trellis Coded Modulation

The #T command enables or disables Trellis Coded Modulation for the 
MT2834MR. There is usually no need to disable (turn-off) Trellis 
Coded Modulation except under an unusual line condition called 
impulse noise. The command AT#T0 turns off Trellis Coded 
Modulation and AT#T1 turns it on. The factory default setting is 
AT#T1.

3.9.5   Miscellaneous Commands

&A      Answerback

The &A command controls the MT2834MR's Answerback feature. 
Answerbacks are used in some on-line realty applications, and 
elsewhere, as a security measure. Due to the security aspect of this 
feature and the fact that there is no requirement for the user to do 
anything with the modem, we will not discuss Answerback here, other 
than to say that it exists and that we recommend you avoid &A in any 
commands or programming.

&B      Transmit Buffer Size

The size of the transmit buffer size is controlled with the &B command. 
It may be desirable to reduce the size of the transmit buffer for certain 
applications. For example, when your modem is receiving a long stream 
of data and the modem at the other end is using speed conversion (the 
serial port speed is greater than the modem baud rate). If you wanted to 
interrupt the current data and request data from a new source, you may 
have to wait for data in the buffer of the sending modem to empty. By 
reducing the transmit buffer size of the sending modem, this wait will 
be reduced. Using the reduced buffer size may cause a slight loss in 
data throughput.

AT&B0 = Normal transmit buffer size 

AT&B1 = Reduced transmit buffer size

The factory default setting is &B0 

$EB     Asynchronous Word Length Command

The MT2834MR has an 11-bit capability when operating 
asynchronously. The $EB command selects between 11-bit and 10-bit 
operation. Type AT$EB1 to enable the modem to function in an 11-bit 
(one start bit, eight information bits, one parity bit and one stop bit) 
format. Type $EB0 (the default setting) to enable a 10-bit (one start bit, 
seven information bits, one parity bit and one stop bit) format.  $EB is 
functional in both Command and On-line mode.  $EB0 automatically 
detects parity when an AT command is issued.

&M      Synchronous/Asynchronous Mode Switching

The &M command is used to set the on-line mode of the MT2834MR 
to either Synchronous or Asynchronous. AT&M0 sets the mode to 
Asynchronous, and all communications will be Asynchronous, both in 
On-line and Command mode. AT&M1 causes the MT2834MR to 
communicate asynchronously when in Command mode, and to switch 
to synchronous mode while on-line.  The factory default setting is 
&M0.

&X      Synchronous Transmit Clock Select

The &X command selects the Synchronous Transmit Clock Source. 
External clocking is when the DTE provides transmit clocking to the 
modem on pin 24 of the RS232C interface. Internal clocking is when 
the modem provides transmit clocking to the DTE on pin 15 of the 
RS232C interface. Internal clocking (&X0) is the factory default 
setting.

The command &X2 selects Slave (External) Clocking. The &X2 
command causes the MT2834MR to generate the Transmit Clock 
timing (pin 15) from the Receive Clock (pin 17) from the DTE, 
(therefore 15 and 17 are the same). In Slave mode, all timing is 
controlled by the receive clock. The position of pin 3 is insignificant 
when in Slave mode.

$AS     AS/400 Support      

The MT2834MR has the ability to function in an IBM AS/400 
environment. The $AS1 command enables AS/400 mode, and causes 
the MT2834MR function with the IBM command set. The $AS0 
command disables this function. 

Note: The MT2834MR must have Command mode and Synchronous 
mode enabled to allow AS/400 mode to be selected. 
The factory default setting is AS/400 mode disabled ($AS0).

$SP     UNIX UUCP Spoofing

The MT2834MR can be configured for a UNIX environment that 
employs ACK flow control as a means  of monitoring data integrity. 
The modem can perform UUCP "spoofing", where the MT2834MR can 
generate ACKs at the DTE interface. Data is transmitted more time 
effectively because the delay of waiting for data to be received, then for 
an ACK to be returned at the remote end, is eliminated. Type $SP1 to 
enable UNIX UUCP spoofing. Type $SP0 to disable UNIX UUCP 
spoofing  (the factory default setting). For more information on the 
UUCP (UNIX-to-UNIX Copy Program) function, refer to your UNIX 
system documentation.

&I      Inactivity Direction

You may use the &I command in conjunction with S-Register S30 to 
select how the Inactivity Timer will work in your modem.  &I controls 
the direction of the inactivity.  S-Register S30 controls the duration of 
the inactivity.  You may turn off the Inactivity Timer, or set the modem 
to respond to inactivity only when receiving, or only when transmitting, 
or to respond to both receiving and transmitting.
	
	&I0     The Inactivity Timer is turned off.
	
	&I1     The Inactivity Timer resets when data is received 
		from the other modem.
	
	&I2     The Inactivity Timer resets when the modem 
		transmits.
	
	&I3     The Inactivity Timer resets when data is either 
		transmitted or received.
		
		The factory default setting is &I0.

*C      Caller ID Detection

Note: The Caller ID detection feature is optional.

The Call Traffic window will display the phone number and the name 
of an individual that dials in on a phone line that supports Caller ID.  
The call must not be answered before the second ring to receive this 
information.  This feautre requires a modem hardware upgrade, Caller 
ID phone lines, and a firmware level greater than 8.07a or 2.07a.  The 
Caller ID firmware is inactive by default, but can be activated via the 
modem AT command, *C.
	
	*C0     Turn off Caller ID detection.
	
	*C1     Turn on Caller ID detection for the 
		MultiModemManager.
	
	*C2     Turn on Caller ID reporting on the serial port by the 
		MultiModemManager.
		
		The factory default setting is *C0.

4.1     Introduction

This chapter covers MT2834MR software registers called S-Registers, 
where certain MT2834MR modem and Command mode configurations 
are stored. Each S-Register is assigned a number (S0, S1, S2, etc.). Use 
the S command to read and/or change the value stored in an S-Register 
(ATSr? to read and ATSr= to change S-Register values). Refer to 
Section 4.2, Reading and Assigning S-Register Values.

S0
Number of Rings until Modem Answers
	Unit:   1 ring          
	Range:  0-255
	Default:        1       
	Description:    S0 defines the number of rings the modem 
waits before answering an incoming call. The default value is one ring 
(Decimal 1), which means that the modem answers the call immediately 
after the first ring. The maximum number of rings that can be 
configured is 255. Setting the value to zero (0) disables auto-answer 
completely.

S1
Rings which have Occurred
	Unit:   1 ring
	Range:  0-255
	Default:        0
	Description:    S1 counts the number of rings that have 
occurred. It is a "read" type of register and is seldom, if ever, used in 
typical operation. Each time an incoming ring signal is detected, S1 
increases its value by one, up to a maximum of 255. If you set S1 to a 
value other than its default value of zero, or if the value is increasing 
with rings, this new value remains stored in S1 for eight seconds after 
the last ring is counted, after which time the value reverts back to zero.

S2
Escape Code Character
	Unit:   ASCII
	Range:  0-127
	Default:        43 (+ sign)
	Description:    S2 defines the escape code character. The 
default character is the plus (+) sign (Decimal 43). It may be set for any 
ASCII character. Setting an S2 value greater than 127 results in no 
escape character, and therefore no means of entering Command mode 
from On-line mode without breaking the on-line connection.

S3
Return Character
	Unit:   ASCII
	Range:  0-127
	Default:        13
	Description:    S3 defines the character recognized as 
Carriage Return (ENTER) or Return. The default setting is CTRL-M 
(Decimal 13), which is the ASCII code for the ENTER key on most 
keyboards. S3 may be set for any ASCII character.

S4
Line Feed Character
	Unit:   ASCII
	Range:  0-127
	Default:        10
	Description:    S4 defines the character recognized as Line 
Feed. The default setting is CTRL-J (Decimal 10), which is the ASCII 
code for the Line Feed key on most keyboards. S4 may be set for any 
ASCII character.

S5
Backspace Character
	Unit:   ASCII
	Range:  0-127
	Default:        8
	Description:    S5 defines the character recognized as 
BACKSPACE. The default setting is CTRL-H (Decimal 8), which is 
the BACKSPACE key on most keyboards. S5 may be set for any ASCII 
character.

S6
Wait Time for Dial Tone
	Unit:   1 sec.
	Range:  2-255, 4-7*
	Default:        2, 4*
	Description:    S6 sets the time the modem waits after the 
ENTER key is pressed before executing a dial command. The default 
setting is two seconds (Decimal 2) or four* seconds.

S7
Time for Carrier (Abort Timer)
	Unit:   1 sec.
	Range:  1-255, 1-45*
	Default:        45
	Description:    S7 defines the Abort Timer (lack of carrier) 
delay time. The default value is 55 seconds (Decimal 55). This means 
that, after dialing, the modem waits for a carrier signal for up to 55 
seconds and, if none is detected, aborts the call. The maximum S7 value 
is 255 (or 45*) seconds.

S8
Pause Time for Comma
	Unit:   1 sec.
	Range:  0-255, 4-7*
	Default:        2, 4*
	Description:    S8 sets the length of the pause caused by a 
comma inserted in a dialing command. The default setting is two 
seconds (Decimal 2) or four* seconds, where each unit is one second. 
S8 may be set for up to 255 seconds.
		
		S8 also sets the time the modem waits before retrying 
a call after detecting a busy signal. Some computer systems need more 
than two seconds to reset (in which case you should increase the value 
of S8).

S9
Carrier Detect Response Time
	Unit:   100 mSec.
	Range:  1-255
	Default:        6
	Description:    S9 sets the time delay between when the 
modem first detects a valid incoming carrier signal and when the 
modem turns on its Carrier Detect circuit. The default setting is 600 
milliseconds, or six units of 100 mSec each (Decimal 6). S9 may be set 
for up to 25.5 seconds.

S10
Carrier Loss Disconnect Delay Time
	Unit:   100 mSec.
	Range:  0-255
	Default:        7
	Description:    S10 sets the time a carrier signal must be lost 
before the modem disconnects. S10 can only be set at speeds of 2400 
bps or less. The default setting is 700 mSec, or seven units (Decimal 7) 
of 100 mSec. Maximum delay is 25.4 seconds (Decimal 254). Setting 
the S10 value to 255 causes the modem to not disconnect with loss of 
carrier.

S11
Tone Dialing: Tone Spacing and Duration
	Unit:   1 mSec.
	Range:  1-255, 80-255*
	Default:        70, 80*
	Description:    S11 sets the speed of tone dialing (spacing 
and tone duration times). The default value is 70 units (Decimal 70) or 
80* units, where each unit is one mSec, meaning that each tone is on for 
70 mSec with a 70 mSec pause between each.
		
		The minimum S11 value allowed by most telephone 
systems is 50 mSec (50 units). Very few telephone systems can handle 
anything faster than that. The maximum S11 value is 255 mSec (255 
units).

S13
Remote Configuration Escape Character
	Unit:   ASCII
	Range:  0-127
	Default:        37 (% sign)
	Description:    S13 defines the remote configuration escape 
character (which becomes your modem's remote configuration 
character). The default is three percent symbols (%%%). When the S13 
character is entered three consecutive times from a remotely connected 
site, your modem responds with its Remote Configuration procedure.

S17
Changing Break Time
	Unit:   10 mSec.
	Range:  0-2500 mSec
	Default:        250 mSec.
	Description:    S17 defines the break time (space) to the PC. 
Break duration is adjustable. The break time is changed in 10 mSec 
increments by increasing or decreasing the value of S17.

S18
Automatic Leased Line Restoral
	Unit:   30 min.
	Range:  10-255 min.
	Default:        30 min.
	Description:    When the MT2834MR is in the dial back-up 
mode of operation, it will periodically check the leased line to 
see if it's operational and try to restore the leased line if possible. The 
frequency of restoral attempts is defined by the contents of S-Register 
S18.                    
		
		The default for S18 is 30 minutes and can be set in 
one minute increments from 10 to 255 minutes. Setting the restoral 
frequency to a value less than 10 minutes causes excessive breaks in the 
dial-up operation.

S19
Dial-Back Timer
	Unit:   1 min.
	Range:  0-255 min.
	Default:        1 min.
	Description:    S19 is a timer that starts when the leased line 
goes down and the modem has determined that the line is bad.  When 
the set time is reached, the originate modem dials the answering 
modem.  The answering modem uses this same timer to determine when 
it will accept the ring. 

S24
PBX/CBX Disconnect Drop Time for DSR/CTS/CD
	Unit:   50 mSec.
	Range:  0-255
	Default:        20 
	Description:    Some PBX and CBX phone systems require 
the modem's DSR, CTS, and/or CD signals to behave in a certain 
manner when calls are disconnected. The MT2834MR's &R, &S, and 
&C commands cause the modem to drop these signals for a specified 
time period upon disconnect, and then bring the signal(s) up again.
		
		S24 defines the length of time that the signals drop. 
The default setting of 20 results in a one second drop time, which is 
what most PBX/CBX systems with this requirement need.

S25
DTR Dropout Time 
	Unit:   100 mSec.
	Range:  0, 1 through 255
	Default:        0 
	Description:    S25 defines the amount of time that DTR 
must be dropped before the modem disconnects. Normally, a disconnect 
occurs when DTR is dropped for 50 milliseconds or more.
		
		The S25 unit value for zero is the default value of 50 
mSec. For values from 1 through 255, the unit value is 100 mSec.

S30
Inactivity Timer
	Unit:   1 min.
	Range:  0-255 
	Default:        0 
	Description:    S30 causes the modem to disconnect if no 
data is transmitted or received for a specified time. This timer runs 
during both Reliable and Normal connections. The timer restarts any 
time a data character is passed through the serial port (either sent or 
received). If noise on the phone line causes an error to be received 
during Normal mode, this also restarts the timer. The inactivity timer is 
disabled by setting S30 to 0, which is the factory default setting.

S32
Time Elapse for Escape Sequence
	Unit:   100 mSec.
	Range:  0-255
	Default:        20
	Description:    S32 sets the time period to validate the 
escape sequence. If the time interval expires before the escape sequence 
is employed (by hitting ENTER), the escape sequence is aborted. The 
default is 20 units (one second).

S34
Buffer Length of Command Mode after On-line Escape Sequence
	Unit:   ASCII
	Range:  0-60
	Default:        10 
	Description:    If the number of characters after AT exceeds 
the S34 buffer length value, the buffer is cleared and the escape 
sequence is aborted.

S36
DTR Busy-out Time Length        
	Unit:   1 sec.
	Range:  0-255 sec.
	Default:        0 sec.
	Description:    S36 sets the amount of time (in seconds) that 
the modem waits when DTR goes off, before going off 
hook (busy).

S37
DTR Busy-in Time Length
	Unit:   1 sec.
	Range:  0-255 sec.
	Default:        5 sec.
	Description:    S37 sets the amount of time (in seconds) that 
the modem waits when DTR comes back on, before 
going on hook.

4.2     Reading and Assigning S-Register Values

The S command reads and assigns S-Register values. To read an S-
Register value, type the letter S followed by the S-register number and a 
question mark (?), then hit ENTER. For example, typing ATS7? and 
hitting ENTER displays the value of S-Register S7 in a 3-digit decimal 
form. The number 8 appears as 008, the number 30 appears as 030, and 
the number 255 appears as 255.

Convert all ASCII characters to their decimal equivalents before 
entering them. S-Register decimal values range from 0-127 for ASCII 
characters, or 0-255 for numeric values. A complete ASCII conversion 
chart is located in Appendix A of this manual.

4.2.1   Examples of Assigning Values

1.      Let's say you wish to have longer pauses caused by the comma 
in a dial command; five seconds instead of two. Typing ATS8=5 
assigns 5 as the value for S-Register S8 (meaning the modem pauses 
five seconds for a comma in a dial command).

2.      In a second example, let's say that you wish to configure the 
MT2834MR modem to answer incoming calls after the 30th ring 
instead of after the first ring. To configure S-Register S0 with a value of 
30, type ATS0=30 and hit ENTER.

4.2.2   Examples of Reading Values

To verify that you entered the value correctly in the above examples, 
type ATS8? and hit ENTER in the first example and ATS0? in the 
second example. You should receive the response 005 in the first 
example and 030 in the second example.  Type ATL6 to list all S-
Registers and their values.

When configuring the S-Registers, it is a good practice to include the 
verification read-entry in the same command line as the configuration 
assignment-entry. In the preceding examples, type ATS8=5S8? and 
ATS0=30S3?.

4.3     AT Commands that Affect S-Registers

Your MT2834MR's default configuration is originating a call to another 
28,800 bps modem that supports error correction, data compression, 
and flow control ("maximum throughput"). If the receiving modem is 
not compatible, the MT2834MR can match any ITU-T or Bell Standard 
modem (but not proprietary protocols).

You may, however, have applications where you do not want this kind 
of maximum throughput (e.g., service not supporting error correction, 
or the V.42 handshake interferes with logon sequence). If so, configure 
the MT2834MR as strictly an auto-answering device or perhaps to 
function in a UNIX environment.

The &W command, used in conjunction with specific other AT 
commands and S-Registers, reconfigures the MT2834MR to conform to 
a specific application. An example of the &W command:

AT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0<CR>

The MT2834MR stores its configuration parameters and S-Register 
values in its nonvolatile memory. The &W0 command stores current 
parameters and values in its nonvolatile RAM. This command also sets 
the modem so that on power up, or when reset with an ATZ command, 
the modem reads all its configuration and S-Register parameters from 
RAM, and not from the factory settings in ROM. The &W command 
changes the configuration parameters stored in RAM that you 
specifically intend to alter. All other default parameters remain 
unchanged. 

The &W1 command sets the modem so that it does not store parameters 
to RAM and, on power up or when an ATZ command is entered, 
parameters are read from the factory default settings in ROM.
Before using the &W command, view the modem's current operating 
parameters. Use the L5, L6, and L7 commands to display the current 
modem configuration.

4.4     Summary

V.42 error correction is built into the MT2834MR's hardware, detecting 
and correcting virtually 100% of transmission errors (usually caused by 
noisy phone lines). When errors are detected, the V.42 protocol causes 
the modem to retransmit the data block in which the error was found.
V.42bis and MNP 5 data compression features are built into the 
MT2834MR's hardware, providing a higher data throughput than the 
modem's modulation speed. The throughput increase depends on the 
type of data transmitted.

The MT2834MR also supports ITU-T Group 3/EIA TR-29 Class 2 fax 
operation. This enables the modem to send and receive text, graphics, 
and images to and from any Group 3 fax machine.

The MT2834MR is set for one of three different modes of operation, 
along with activating data compression in Reliable mode. Normal mode 
(&E0) disables error correction, Reliable mode (&E2) turns it on, and 
Auto-Reliable mode (&E1) lets the modem automatically turn V.42 on 
when it detects its use in another modem.

Flow control methods are used by the MT2834MR to prevent data loss 
from buffer overflow. The modem both initiates flow control and 
responds to pacing, using either Xon/Xoff commands or RS232C/V.24 
signaling via CTS (from the modem) or RTS (from the 
computer/terminal). Hewlett-Packard ENQ/ACK is also supported. If 
needed, Xon/Xoff commands are passed through the modem to a 
remote computer or terminal.

The MT2834MR's speed conversion feature lets the modem operate at 
one speed over the telephone line and another speed over the 
RS232C/V.24 serial port. This lets the computer communicate with the 
modem at a fixed speed of up to 115,200 bps, while the modem 
operates at various rates of up to 28,800 bps (V.34 enabled). This 
ability is vital for data compression, since your computer must send 
data to the modem at a higher speed than the rate at which the modem is 
sending data over the phone line.
