Multitech MultiModem MT2834MR6 User manual

MultiModem
MT2834MR6
User Guide

MultiModem MT2834MR6 User Guide
PN: S000326A
Copyright ©2003 by Multi-Tech Systems, Inc.
All rights reserved. This publication may not be reproduced, in whole or in part, without prior written permission from 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.
Revision Date Description
A 12/30/2003 Initial release of MT2834MR6 User Manual on CD.
Trademarks
Trademarks of Multi-Tech Systems, Inc. are as follows: MultiExpress, MultiExpressFax, MultiModemII, Multi-Tech and the
Multi-Tech logo. Windows is a registered trademark of Microsoft Corporation.
Technical Support
France [email protected] [phone]
India [email protected] [phone]
U.K. [email protected] [phone]
U.S., Canada [email protected] [phone]
Rest of World [email protected] [phone]
World Headquarters
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112 U.S.A.
[phone] or [phone]
U.S. FAX [phone]
Technical Support [phone]
www.multitech.com

Contents
Chapter 1 - Introduction..................................................................................... 7
1.1 Introduction ............................................................................................. 8
1.2 ManualOrganization............................................................................... 8
1.3 Description ............................................................................................. 9
1.4 FCC Regulations forTelephone Line Interconnection........................... 10
1.4.1 FCCFaxUpdate .................................................................................10
1.5 Canadian Limitations Notice................................................................. 11
1.6 Technical Specifications ....................................................................... 12
1.7 Power Supply ....................................................................................... 14
1.8 Modem LED Indicators ......................................................................... 15
1.9 Busy Switch ......................................................................................... 15
1.10 MT2834MR6Installation Notes ............................................................. 16
1.11 Safety Warnings ................................................................................... 16
Chapter 2 - Dialing and Answering ................................................................. 17
2.1 Introduction ........................................................................................... 18
2.2 Dial-UpAutomaticAnswering ............................................................... 18
2.3 Dial-UpHandshaking Details................................................................ 18
2.4 CallTermination.................................................................................... 19
Chapter 3 - AT Commands .............................................................................. 20
3.1 Working with AT Commands................................................................ 21
3.1.1 ModesofOperation ............................................................................21
3.2.2 CommandStructure ............................................................................22
3.3.3 CommandEditing ...............................................................................22
3.2 Dialing Commands............................................................................... 26
3.3 Dial Modifier Commands ...................................................................... 27
3.4 Phone Number Memory Commands.................................................... 30
3.5 Configuration Storage and Recall Commands ..................................... 32
3.6 Modem Response (Result Code) Commands..................................... 34
3.7 Online Connection Commands ............................................................ 36
3.8 V.34 Commands................................................................................... 40
3.9 RS-232 Interface Commands .............................................................. 41
3.10 Error Correction and Data Compression Commands.......................... 43
3.11 Speed Conversion Commands ............................................................ 45
3.12 Immediate Action Commands .............................................................. 47
3.12 Flow Control Commands ..................................................................... 49

3.13 Escape Sequences .............................................................................. 52
3.14 Remote Configuration Commands....................................................... 53
3.15 Line Probe Commands ........................................................................ 54
3.16 Diagnostic Commands......................................................................... 55
Chapter 4 - S-Registers.................................................................................... 56
4.1 Introduction ........................................................................................... 57
4.2 S-Registers .......................................................................................... 57
4.3 Reading andAssigning S-Register Values ........................................... 63
4.3.1 Examples of Assigning Values ...........................................................63
4.3.2 Examples of Reading Values..............................................................63
4.4 AT Commands Affecting S-Registers................................................... 64
Chapter 5 - Error Correction, Data Compression & Speed Conversion..... 65
5.1 Introduction ........................................................................................... 66
5.2 How V.42 Detects and Corrects Errors ................................................ 67
5.3 Data Compression ............................................................................... 68
5.4 MNP Classes........................................................................................ 68
5.5 V.42 Mode Select Command (#L)......................................................... 69
5.5.1 #L0Command.....................................................................................69
5.5.1.1 OriginateMode ................................................................................69
5.5.1.2 AnswerMode...................................................................................69
5.5.2 #L1Command.....................................................................................69
5.5.3 #L2Command ....................................................................................69
5.5.4 #L3Command.....................................................................................69
5.6 Modes of Operation .............................................................................. 70
5.6.1 Non-ErrorCorrectionMode(&E0)........................................................70
5.6.2 ReliableMode(&E2) ...........................................................................70
5.6.3 AutoreliableMode(&E1) .....................................................................70
5.7 Flow Control ......................................................................................... 71
5.8 Modem-InitiatedFlow Control ............................................................... 72
5.8.1 XON/XOFFFlowControl(&E5)...........................................................72
5.8.2 HardwareFlowControl(&E4) ..............................................................72
5.9 Pacing (&E13) ...................................................................................... 73
5.9.1 XON/XOFFPass-Through(&E7) ........................................................73
5.9.2 Non-ErrorCorrectionModeFlowControl(&E10and&E11).................73
5.9.3 HewlettPackardENQ/ACKPacing(&E9)...........................................73
5.10 Compression, Error Correction, Flow Control,
and Pacing Commands........................................................................ 74
5.10.1 V.42ErrorCorrectionModes ..............................................................74
5.10.2 Modem-InitiatedFlowControl .............................................................74
5.10.3 XON/XOFFPass-Through ..................................................................74
5.10.4 HewlettPackard ENQ/ACK Pacing.....................................................74
5.10.5 Non-ErrorCorrectionModeFlowControl .............................................74

5.10.6 Pacing(Computer-InitiatedFlowControl)............................................74
5.10.7 DataCompression ..............................................................................74
5.11 Result Codes........................................................................................ 75
5.11.1 MNPErrorCorrection..........................................................................75
5.11.2 LAP-MErrorCorrection.......................................................................75
5.11.3 DataCompression ..............................................................................75
5.12 Speed Conversion ................................................................................ 75
5.12.1 Baud Adjust ($BA) .............................................................................. 76
5.12.2 ModemBaudRate($MB)....................................................................76
5.12.3 Serial Port Baud Rate ($SB) ............................................................... 77
5.13 Related Commands ............................................................................. 78
5.13.1 AutoreliableBuffering($A) ..................................................................78
5.13.2 Maximum Block Size (&BS) ...............................................................78
5.13.3 AutoreliableFallbackCharacter($F) ...................................................78
5.13.4 RetransmitCount($R) ........................................................................79
5.13.5 V.42ErrorCorrectionat300bps($E) .................................................79
5.14 Summary.............................................................................................. 79
Chapter 6 - Testing & Troubleshooting.......................................................... 80
6.1 Introduction ........................................................................................... 81
6.2 LocalAnalog Loopback Test (V.54 Loop 3) ........................................... 82
6.2.1 TestProcedure ...................................................................................82
6.3 Remote Digital Loopback Test (V.54 Loop 2)........................................ 83
6.3.1 TestProcedure ...................................................................................83
6.4 Local Digital Loopback Test (V.54 Loop 2)............................................ 84
6.4.1 TestProcedure ...................................................................................84
Chapter 7 - Warranty & Service....................................................................... 85
7.1 Multi-Tech Systems, Inc. Warranty & Repairs Policies......................... 86
7.1.1 Warranty .............................................................................................86
7.1.2 U.S.andCanadianCustomers............................................................86
7.1.3 InternationalCustomers(outsideU.S.A.andCanada)........................87
7.1.4 InternationalDistributors .....................................................................87
7.2 Repairs................................................................................................. 88
7.2.1 RepairProceduresforU.S.andCanadianCustomers ........................88
7.2.2 RepairProceduresforInternationalCustomers...................................88
7.2.3 RepairProceduresforInternationalDistributors..................................89
7.2.4 ReplacementParts .............................................................................89
7.3 Technical Support................................................................................. 89
7.4 InternetSite .......................................................................................... 89
Appendices........................................................................................................ 90
AppendixA..................................................................................................... 91
ASCIIConversionChart...................................................................................91

AppendixB .................................................................................................... 92
Dial Pulses ......................................................................................................92
ToneDialFrequencies .....................................................................................93
AppendixC .................................................................................................... 94
ResultCodeSummary.....................................................................................94
AppendixD .................................................................................................... 96
S-RegisterSummary .......................................................................................96
AppendixE .................................................................................................... 98
ATCommandSummary ..................................................................................98
AppendixF................................................................................................... 106
RS-232CInterfaceSpecifications .................................................................. 106
FunctionalDescriptionof theRS-232C Signals ............................................. 107
Transmitted Data (TD) — Pin 2 ...................................................................... 107
Received Data (RD) — Pin 3.......................................................................... 107
RequestTo Send (RTS) — Pin 4 .................................................................... 107
ClearTo Send (CTS) — Pin 5......................................................................... 107
Data Set Ready (DSR) — Pin 6 ..................................................................... 107
Signal Ground (SG) — Pin 7 .......................................................................... 107
Carrier Detect (CD)— Pin 8 ........................................................................... 107
TestVoltage (+V) — Pin 9 .............................................................................. 108
High Speed (HS) — Pin 12............................................................................. 108
Transmit Clock (TC) — Pin 15........................................................................ 108
Receive Clock (RC) — Pin 17 ........................................................................ 108
DataTerminal Ready (DTR) —Pin 20 ............................................................ 108
Ring Indicator (RI) — Pin 22 .......................................................................... 109
ExternalTransmit Clock (XTC) — Pin 24........................................................ 109
Terminal Busy (OOS) — Pin 25...................................................................... 109
AppendixG .................................................................................................. 110
CableandConnectorDiagrams ..................................................................... 110
APPENDIXH ................................................................................................111
Introduction to MultiTech Escape Methods ................................................... 111
How to Select an Escape Method..................................................................112
Escape Method 1:+++AT<CR> ..................................................................... 112
Escape Method 2:<BREAK>AT<CR> ........................................................... 112
S-RegistersandEscape Sequence ............................................................... 113
Abortingan EscapeSequence ...................................................................... 113
APPENDIXI................................................................................................. 114
IntroductiontoRemoteConfiguration............................................................. 114
BasicProcedure ............................................................................................ 114
Setup 114
ChangingthePasswords ............................................................................... 115
ChangingtheRemoteEscapeCharacter ....................................................... 115
Index................................................................................................................. 116

Chapter 1 - Introduction

8
Chapter 1 - Introduction
1.1 Introduction
Welcome to the world of data communications. You have acquired one of the finest rack-mount intelligent
modems available, the MT2834MR6, from Multi-Tech Systems. This owner’s manual will help you install,
configure, test, and use your modem.
Your MT2834MR6 is designed to operate as an enhanced ITU-T V.34 dial-up modem. As such, it includes
the advanced features of Multi-Tech standalone modems, such as the popular MultiModemZDXb.
This manual documents all of the MT2834MR6’s features and capabilities, such as autodial, autoanswer,
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 described, so you
will know where to turn for specific information.
1.2 Manual Organization
Chapter 1 Introduction and Description
This chapter describes the MT2834MR6 and its LED indicators, gives its technical specifications, and
provides a guide to the organization of the manual.
Chapter 2 Dialing and Answering
This chapter describes answer mode operation in detail, including handshaking procedures between two
modems and an autoanswer application. Various methods of call termination are also described.
Chapter 3 Command Mode Operation
This chapter provides an introduction to MT2834MR6 command mode fundamentals, followed by a detailed
explanation of each AT command, providing examples where applicable.
Chapter 4 S-Registers
This chapter describes the MT2834MR6’s S-registers, which are used to store various modem options. Each
S-register is defined and explained.
Chapter 5 Error Correction, Data Compression and Speed Conversion
This chapter provides detailed information about some of the advanced features of the MT2834MR6, namely,
V.42 error correction, data compression, speed conversion, and other features that improve throughput.
Chapter 6 Testing the MT2834MR6
This chapter describes loopback testing for the MT2834MR6.
Chapter 7- Warranty, Service, and Technical Support
This chapter provides the terms of the MT2834MR6’s warranty, instructions for obtaining factory service, and
information about Multi-Tech’s BBS and technical support. Information on upgrading the MT2834MR6’s
firmware is also provided.
Appendices
This chapter includes sections pertaining to ASCII/HEX/Decimal Conversion Chart, Dial Pulses and Tone
Dial Frequencies, Result Code Summary, S-Register Summary, AT Command Summary, RS-232 Interface
Specifications, Cable and Connector Diagrams, Escape Methods, and Remote Configuration.

9
Chapter 1 - Introduction
1.3 Description
Each MT2834MR6 card contains six integrated 33,600 bps MultiModems. Each modem on the MT2834MR6
card can be configured independently of the others via the MultiModemManager controller card (Model
MR4800 or MR4800E), which can support and control up to 16 MultiModem cards per rack. Refer to your
MultiModemManager
Owner’s Manual for more information about the rack and its components.
Perhaps the most significant extras incorporated in the MT2834MR6 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 MT2834MR6 offers interactive automatic dialing capability, as well as command mode option
configuration. Two dial command strings, of up to 60 digits each, can be stored in each modem’s nonvolatile
memory. The modem supports both pulse and tone dialing, and can recognize dial tones and busy signals
for reliable call-progress detection.
The MT2834MR6 is registered by the FCC for direct connection to the public telephone networks. No Data
Access Arrangements (DAAs) are required.
The MT2834MR6 is fully compatible with the standard AT command set, and is therefore compatible with all
popular communications software packages.

10
Chapter 1 - Introduction
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 MT2834MR6 is
installed:
a. The particular phone line (phone number) to which the connection is to be made.
b. The FCC Registration Number: AU7USA-30805-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: RJ-11C or RJ-11W (single line)
e. The manufacturer’s name and model number: Multi-Tech Systems - Model MT2834MR6
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 your fax software manual for setup details.

11
Chapter 1 - Introduction
1.5 Canadian Limitations Notice
Notice: The ringer equivalence number (REN) assigned to each terminal device provides an indication of the
maximum number of terminals allowed to be connected to a telephone interface. The termination of a
interface may consist of any combination of devices subject only to the requirement that the sum of the ringer
equivalence numbers of all the devices does not exceed 5.
Notice: The Industry Canada label identifies certificated equipment. This certification means that the
equipment meets certain telecommunications network protective, operational and safety requirements.
Industry Canada 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. 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.
Caution: Users should not attempt to make such connections themselves, but should contact the appropriate
electric inspection authority, or electrician, as appropriate.
Industry Canada Certification Number:
Ringer Equivalence Number (REN): 0.2

12
Chapter 1 - Introduction
1.6 Technical Specifications
Model Number MT2834MR6
Data Rates (Modem) Six independent modems (Modem A, B, C, D, E, F), 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 Rates (Fax) 14,400, 9600, 4800, and 2400 bps
Data Format (Modem) Serial, binary, asynchronous at all data rates
Configuration Each of the card’s six modems is independently configurable
Compatibility(Modem) ITU-T V.42bis, V.42, V.34, AT&T V.32terbo, ITU-T V.32bis, V.32, V.25bis, V.21,
V.22bis, V.22, V.23, V.17, Bell 212A* and 103/113*
Compatibility (Fax) ITU-T Group 3, T.4, T.30, V.21, V.27ter, V.29, V.17, and EIA TR29.2
Error Correction ITU-T V.42 (MNP® Classes 3 and 4, and LAP-M)
Data Compression ITU-T V.42bis (4:1 throughput) or MNP 5 (2:1 throughput)
Speed Conversion Serial port data rates adjustable to 300, 1200, 2400, 4800,9600, 19,200, 38,400,
57,600, and 115,200 bps
FlowControl XON/XOFF,CTS/RTS,ENQ/ACK
Mode of Operation Half or full duplex over dial-up lines; automatic or manual dialing, automatic or
manual answer
Intelligent Features Fully 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; nonvolatile memory; on-screen displays of
modem parameters, stored telephone numbers, and help menus; and remote
configuration.
AT Commands 100% compatible with standard AT command set
Command Buffer 60 characters
Automatic Dialing Standard AT command asynchronous dialing
ModemModulations FSK at 300 bps, PSK at 1200 bps, QAM at 2400, 4800, and 9600 bps (non-trellis),
QAM with trellis-coded modulation (TCM) at 9600, 12,000, 14,400, 16,800, 19,200,
21,600, 24,000, 26,400, 28,800, 31,200, and 33,600 bps
FaxModulations V.21 CH2 FSK at 300 bps
V.27ter DPSK at 4800 and 2400 bps
V.29 QAM at 9600 and 7200 bps
V.17TCM at 14400, 12000, 9600, and 7200 bps
Carrier Frequencies 1600, 1646, 1680, 1800, 1829, 1867, 1920,
ITU-T V.34 1959, 2000 Hz
Carrier Frequencies: 1800 Hz
AT&T V.32 terbo/
ITU-T V.32bis/V.32
Carrier Frequencies: Transmit originate: 1200 Hz
V.22bis/V.22 or Transmit answer: 2400 Hz
Bell 212A Standard Receive originate: 2400 Hz
(2400 & 1200 bps) Receive answer: 1200 Hz

13
Chapter 1 - Introduction
Carrier Frequencies: Transmit originate: 1270 Hz mark
Bell 103/113 1070 Hz space
(300 bps) Receive originate: 2225 Hz mark
2025 Hz space
Transmit answer: 2225 Hz mark
2025 Hz space
Receive answer: 1270 Hz mark
1070 Hz space
Carrier Frequencies: Transmit originate: 980 Hz mark
V.21 1180 Hz space
Receive originate: 1650 Hz mark
1850 Hz space
Transmit answer: 1650 Hz mark
1850 Hz space
Receive answer: 980 Hz mark
1180 Hz space
Carrier Frequencies: Transmit originate: 390 Hz mark
V.23 450 Hz space
Receive originate: 1300 Hz mark
2100 Hz space
Transmit answer: 1300 Hz mark
2100 Hz space
Receive answer: 390Hz mark
450Hz space
FaxModulations 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, 1850 Hz space for transmit originate
1650 Hz mark, 1850 Hz space for transmit answer
V.27ter: 1800 Hz Originate/Answer
V.29 QAM: 1700 Hz Originate/Answer
V.17 TCM: 1800 Hz Originate/Answer
Transmit Level -13 dBm
Frequency Stability +0.01%
Receiver Sensitivity -43 dBm under worst case conditions
AGC Dynamic 43 dB
Range
Serial Interface EIA RS-232C
Diagnostics Power-on self-test; ITU-T V.54 local analog loop, local digital loop, remote digital
loop.

14
Chapter 1 - Introduction
Firmware Upgrades Via flash PROM technology on Multi-Tech’s BBS
Indicators LEDs for Transmit Data, Receive Data, Carrier Detect, Speed, and Off Hook/Out-
Of-Service
Controls Toggle switches for busy-out
Environmental Temperature range: 0°–50° C (32°–120° F)
Humidity range: 20–90% (noncondensing)
Power 5 VDC at 0.95 A
Requirements ±16 VDC at 0.1 A
PowerConsumption Approximately 6 watts
Dimensions, .9 × 11 × 15 in. (2.2 × 28 × 37 cm) H × W × D
card modem
Weight 2.5 lb. (1.1Kg)
Limited Warranty Two years
Fuses F1 (+5V), F2 (-16V), F3 (+16V)
1.7 Power Supply
DC voltages are supplied to all modems in the CC4800A rack through one or two PS4800A power supplies,
designed for conventional 115 or 230 VAC connection. The power supply is a universal input switching
power supply.

15
Chapter 1 - Introduction
1.8 Modem LED Indicators
The MT2834MR6 has five LED indicators per modem:
TD Transmit Data. 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 TD circuit on Pin 2 of the RS-232C interface.
RD Receive Data. This LED blinks when data is received, on for a space, off for a mark. The state of
this LED matches that of the RD circuit on Pin 3 of the RS-232C interface.
CD Carrier On. This LED lights when a valid carrier tone has been detected.
Speed Speed. This LED blinks at different rates to indicate the speed of the data connection:
Data Rate (bps) LED State
12000 or less Off
14400 or 16800 Slow blink rate
19200 or 21600 Medium blink rate
24000 or 26400 Fast blink rate
28800 or more On
OH/OOS Off Hook/Out of Service. This LED lights when the modem is off hook, which occurs when the
modem is dialing, online, or answering a call. The LED flashes when the modem is in the busy-
out or out-of-service state.
Note: The PS4800 modem rack power supply has one LED that indicates the presence of all supply voltages.
1.9 Busy Switch
The MT2834MR6 has six two-position Busy switches on the front panel. Each switch can be used to create a
“busy-out” (OOS) condition for one of the six on-board modems (i.e., modem A, B, C, D, E, or F).
To place a modem in the Busy condition, move the appropriate Busy switch to the right. The selected modem
goes off-hook, its OH/OOS LED begins to flash, 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 rollover to the next available modem while you
check the status of the Busy modem.
Note: The MultiModemManager can perform the same function using software.

16
Chapter 1 - Introduction
1.10 MT2834MR6 Installation Notes
All installation must be done by a qualified service person.
The installation instructions in your MultiModemManager
Owner’s Manual include information about the use
of blanking plates to cover empty slots in the card frame. Be sure to follow those instructions.
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 MT2834MR6K 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 he speechband circuit.
2. The apparatus shall comprise only
a. apparatus approved 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.
1.11 Safety Warnings
•Never install telephone wiring during a lightning storm.
•Never install telephone jacks in wet locations unless the jacks are specifically designed for wet locations.
•Never touch uninsulated telephone wires or terminals unless the telephone line has been disconnected at
the network interface.
•Use caution when installing or modifying telephone lines.
•Avoid using a telephone (other than a cordless type) during an electrical storm. There may be a remote
risk of electrical shock from lightning.
•Do not use the telephone to report a gas leak in the vicinity of the leak
•Ports that are connected to other apparatus are defined as SELV. To ensure conformity to EN 41003,
ensure that these ports are only connected to the same type on the other apparatus.

Chapter 2 - Dialing and Answering

18
Chapter 2 - Dialing and Answering
2.1 Introduction
This chapter describes the dialing and answering capabilities of the MT2834MR6 modems, which are
standard ITU-T V.34 full duplex dial-up modems.
2.2 Dial-Up Automatic Answering
The MT2834MR6 can answer calls automatically. The MT2834MR6 is in originate mode in its idle state.
When it detects an incoming call, it automatically switches to answer mode. You can program the modem to
answer a call after a certain number of rings by using register S0 (see Chapter 4).
2.3 Dial-Up Handshaking Details
This section briefly explains what happens between two modems in a normal call. We are assuming that
there are MT2834MR6s 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 indicator
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 on pin 20 of the RS-232C interface. This signal comes from the computer or terminal to which
the modem is connected.
Note: If you are using reliable or auto-reliable mode, some additional handshaking takes place. This is
explained in Chapter 5, in the “Auto-Reliable Mode” section.

19
Chapter 2 - Dialing and Answering
2.4 Call Termination
There are several methods by which you can terminate a call, or simply stated, hang up:
1. Command Mode Control. It is possible to enter command mode while remaining online by entering an
escape sequence ( +++AT<CR> in most cases). From command mode, you can return to the online state
by typing
ATO , or you can terminate the call by using the H command. Typing ATH will hang up the line
(bring it on-hook). So the command to hang up a call is three plus signs followed by
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 autoanswer end of
the line to cause the calling modem to disconnect after logoff procedures.
3. Loss of Carrier. Once a data connection has been established, the modem will disconnect if a loss of
carrier occurs for 700 milliseconds (0.7 seconds) or longer. This time can be configured with 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 starts a 45 second timer
and waits for a carrier signal from the originating modem. If a carrier is not detected within this period, the
modem disconnects (hangs up) and is ready for another call. Originate Mode: The abort timer functions
the same as in the answer mode, except that the timer begins 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 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 reset anytime a character passes through the serial port in either a
send or receive direction. This function is controlled by 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 number of minutes selected
by register
S30 .

Chapter 3 - AT Commands