Multitech MT2834MR User manual

PN 88300150
4/3/01 1
MT2834MR, MT2834MRI, and
MT2834MRK
Owner’s Manual

PN 88300150
4/3/01 2
MT2834MR, MT2834MRI, MT2834MRK
Owner’s Manual
MOD PN 88300150 Version 1.00 - 4/3/01
(Replaces Manual PN 82035706 Rev. G)
This publication may not be reproduced, in whole or in part, without prior expressed written permission from Multi-
Tech Systems, Inc. All rights reserved.
Copyright © 1996, by Multi-Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and specifically
disclaims any implied warranties of merchantability or fitness for any particular purpose. Furthermore, Multi-Tech
Systems, Inc. reserves the right to revise this publication and to make changes from time to time in the content
hereof without obligation of Multi-Tech Systems, Inc. to notify any person or organization of such revisions or
changes.
Record of Revisions
Revision Date Description
F08/19/96 Manual revised to include technical and editorial changes
throughout the manual.
G11/11/96 Manual revised to include the Firmware Version 1.11 Product
Update, PN 82053850.
H4/3/01 Manual revised and reformatted for distribution on diskette.
TRADEMARKS
Trademarks of Multi-Tech Systems, Inc. are as follows: MultiModem, MultiModemII, MultiModemManager,
MultiExpress, MultiExpressFax, Multi-Tech and the Multi-Tech logo.
MNP and Microcom Network Protocol are trademarks of Microcom Inc.
AS/400 and System/3x is a trademark of IBM.
Macintosh is a trademark of Apple Computer Inc.
Unix is a trademark of X/Open Co. Ltd.
AT&T is a trademark of American Telephone and Telegraph Company.
PATENTS
This device covered by one or more of the following patents: 6,031,867; 6,012,113; 6,009,082; 5,905,794;
5,864,560; 5,815,567; 5,815,503; 5,812,534; 5,809,068; 5,790,532; 5,764,628; 5,764,627; 5,754,589; D394,250;
5,724,356; 5,673,268; 5,673,257; 5,644,594; 5,628,030; 5,619,508; 5,617,423; 5,600,649; 5,592,586; 5,577,041;
5,574,725; D374,222; 5,559,793; 5,546,448; 5,546,395; 5,535,204; 5,500,859; 5,471,470; 5,463,616; 5,453,986;
5,452,289; 5,450,425; D361,764; D355,658; D355,653; D353,598; D353,144; 5,355,365; 5,309,562; 5,301,274
Other Patents Pending
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112 U.S.A.
[phone] or [phone]
U.S. Fax [phone]
Technical Support [phone]
Internet Address: http://www.multitech.com

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CHAPTER 1 - INTRODUCTION AND DESCRIPTION
1.1 Introduction.................................................................................6
1.2 How To Use This Manual ...........................................................6
1.3 Description..................................................................................7
1.4 FCC Regulations for Telephone Line Interconnection................8
1.5 Canadian Limitations Notice.....................................................10
1.6 Compliance with BABT Requirements (MT2834MRK only).....11
1.7 Technical Specifications...........................................................11
1.8 Power........................................................................................13
1.9 Modem LED Indicators.............................................................13
1.10 BUSY Switch.............................................................................14
1.11 Controls on PC Board...............................................................14
1.12 MT2834MRK Installation Notes................................................14
CHAPTER 2 - DIALING AND ANSWERING
2.1 Introduction...............................................................................15
2.2 Automatic Leased Line Restoral Operation..............................15
2.3 Manual Dial Backup Call Termination.......................................15
2.4 Dial Back-up Leased Line Restoral ..........................................16
2.5 Dial-up Automatic Answering....................................................16
2.6 Dial-up Handshaking Details ....................................................16
2.7 Call Termination........................................................................16
CHAPTER 3 - COMMAND MODE OPERATION
3.1 Introduction...............................................................................18
3.2 Typographic Conventions Used in This Manual.......................18
3.3 Functional Modes .....................................................................19
3.4 AT Commands..........................................................................21
3.5 Result Codes ............................................................................24
3.6 Command Mode Fundamentals ...............................................26
3.7 Dialing Commands ...................................................................32
3.8 Immediate Action Commands...................................................34
3.9 Configuration Commands.........................................................36
CHAPTER 4 - S-REGISTERS
4.1 Introduction...............................................................................38
4.2 Reading and Assigning S-Register Values...............................38
4.3 AT Commands that Affect S-Registers.....................................42
4.4 Summary...................................................................................43
CHAPTER 5 - ERROR CORRECTION, DATA COMPRESSION AND
SPEED CONVERSION
5.1 Introduction...............................................................................45
5.2 How V.42 Detects and Corrects Errors.....................................46
5.3 Data Compression....................................................................47
5.4 MNP Classes............................................................................48
5.5 V.42 Mode Select Command (#L) ............................................48
5.6 Modes of Operation ..................................................................49
5.7 Introduction to Flow Control......................................................49
5.8 Modem-Initiated Flow Control...................................................50
5.9 Terminal/Computer-Initiated Pacing (&E13).............................50
5.10 Xon/Xoff Pass-Through (&E7)..................................................51
5.11 Normal Mode Modem Flow Control (&E10 and &E11).............52
5.12 Hewlett Packard ENQ/ACK Pacing (&E9)................................52

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5.13 Compression, Error Correction, Flow Control,..........................53
5.14 Pass Through and Pacing Commands.....................................54
5.14 Error Correction Result Codes..................................................54
5.15 Speed Conversion ....................................................................55
5.16 Related Commands..................................................................55
5.17 Summary...................................................................................56
CHAPTER 6 - TESTING YOUR MODEM
6.1 Introduction ..............................................................................57
6.2 Local Analog Loopback Test/V.54 Loop 3 ...............................57
6.3 Digital Loopback Test/V.54 Loop 2 (Local/Manual)..................57
6.4 Digital Loopback Test/V.54 Loop 2 (Remote/Automatic)..........58
6.5 Back-to-Back Test ....................................................................59
6.6 Synchronous Mode Testing......................................................60
6.7 Local Analog Loopback Test (Sync. Mode)..............................61
6.8 Digital Loopback Test (Local/Manual) (Sync. Mode)................62
6.9 Digital Loopback Test (Remote/Automatic) (Sync. Mode)........63
CHAPTER 7 - DIP-SWITCHES AND JUMPERS
7.1 Introduction...............................................................................64
7.2 16-Position DIP-Switches.........................................................65
7.3 16-Position DIP-Switch Settings...............................................68
7.4 Jumper Settings........................................................................70
CHAPTER 8 - SERVICE, WARRANTY & TECH SUPPORT
8.1 Introduction...............................................................................72
8.2 Limited Warranty.......................................................................72
8.3 Tech Support ............................................................................72
8.4 Service......................................................................................72
8.7 How to Find Multi-Tech on the Internet.....................................73
8.9 Upgrading the MT2834MR Firmware .......................................73
APPENDICES
Appendix A - ASCII Codes/Hex/Decimal Conversion Chart............74
Appendix B - Dial Pulse and Tone Frequencies..............................75
Appendix C - DIP-Switch Summary.................................................77
Appendix D - Result Code Summary...............................................78
Appendix E - S-Register Summary..................................................80
Appendix F - AT Command Summary.............................................81
Appendix G - V.25bis Operation ......................................................85
Appendix H - RS232C Interface Specifications...............................93
Appendix I - Cable and Connector Diagrams.................................96
Appendix J - Escape Methods Used by Multi-Tech Systems .......100
Appendix K - Remote Configuration..............................................103
Appendix L - MT2834MRI PC Board ............................................104

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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 33,600 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 33,600 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.

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Chapter 6 - Testing Your Modem
This chapter provides information on loopback testing for your MT2834MR.
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.
Chapter 8 - Service, Warranty and Tech Support
This chapter provides instructions for getting modems serviced at the factory, a statement of limited two-
year warranty and information about Multi-Tech's Technical Support. Information on the modem upgrade
feature is also provided.
Appendix A - ASCII/HEX/Decimal Conversion Chart
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 I - Cable and Connector Diagrams
Appendix J - Escape Sequences Used by Multi-Tech Systems
Appendix K - Remote Configuration
Appendix L – MT2834MRI PC Board
1.3 Description
Each MT2834MR card has three integrated 33,600 bps MultiModems. Each of the three modems on the
MT2834MR card can be configured independently from each other via the MultiCommManager (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 MultiCommManager 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.

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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.
1.4.1 FCC Fax Update
The Telephone Consumer Protection Act of 1991 makes it unlawful for any person to use a computer or
other electronic device to send any message via a telephone fax machine unless such message clearly
contains in a margin at the top or bottom of each page or the first page of the transmission, the date and
time it is sent and an identification of the business or other entity, or other individual sending the message
and the telephone number of the sending machine or such business, other entity, or individual.
See the cover page of your fax software manual for setup details.
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.

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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.

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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 Auto Call 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.

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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 33,600, 31,200, 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, 28,800, 31,200, or 33,600 bps;
synchronous at 1200, 2400, 4800, 9600, 14,400, 16,800, 19,200, 21,600, 24,000,
26,400, 28,800, 31,200, or 33,600 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, Bell 212A* and 103/113*
Error Correction MNP®Classes 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

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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 33,600, 31,200, 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 300 bps
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

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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 web site
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 0oto 50o(32o to 120o F)
Temperature
Power 5 Volts DC at 0.95 Amp
Requirements +/-16 Volts DC at 0.1 Amp
Power ConsumptionApproximately 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.

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4/3/01 13
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. This LED
blinks slowly (1 blink per second) when the modem is set for 31,200 bps operation. This LED blinks
quickly (5 blinks per second) when the modem is set for 33,600 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 (9600). 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
MultiCommManager Software installed, a full suite of modem tests can be controlled from a central PC.
Refer to the MultiCommManager 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 MultiCommManager can perform the same
function using software.

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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
MultiCommManager 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.

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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.

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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.

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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. This time can be configured with S-Register
S10 for any time from 0 to 25.5 seconds (in 100 mSec increments). 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.
S10 has no effect at connections above 2400 bps.
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 factory default setting, or set to time out after the time (in
minutes) selected by S-Register S30.

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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.

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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 also 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.
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*
HHook on/off control, or Hang up
$H Help screens
*H Busy out after disconnect
I Identify modem model/revision
#L V.42 mode select (LAP-M/MNP)
LList 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

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$MBn Modem Baud Rate
Nd Dial Stored Telephone Number
NdNe Number Linking
OOn-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
*Rn Ring message on callback modem
&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
TTone dial
#T Enable/Disable Trellis Coded Modulation
&Tn Recognise RDL signal
U U-loop test
Vn Verbose or Terse result codes
#V User control of V.32terbo in Answer Mode
W Wait for new dial tone
&Wn Store configuration in RAM
XExtended 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.