Multi-Tech Systems MT2834BA Series manual Phone Line Conditioning Commands, Bell/V.21 Tone

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Chapter 5 - Command Mode

5.4.6Phone Line Conditioning Commands

Guard Tones (Not Used in BAI/BLI Models) &G

The &G command is used to control the presence or absence of guard tones from the transmitter when in Answer mode, at either 1200 or 2400 bps. Guard tones are used in Europe and other areas for the modem to function in the telephone systems. Guard tones are not used in the United States. &G0 (default), turns off CCITT guard tones. &G1 turns on 550 Hz guard tones. &G2 turns on 1800 Hz guard tones. This command is not used in international models.

Bell/V.21 Tone

B

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

The ATB0 command enables CCITT frequencies including V.21 (300 bps) and V.23 (1200/75 bps). The ATB1 command enables Bell frequencies including Bell 103 (300 bps). The modem default is ATB0.

Phone Line Monitoring Speaker M

The modem has an internal on-board, speaker which functions like the speaker in a telephone handset to enable you to monitor phone line activity. The M command can be used to determine when the speaker is operational.

Entering ATM0 disables the speaker completely, while ATM1 causes the speaker to be on only until a carrier signal is detected. ATM2 causes the speaker to remain on at all times. ATM3 causes the speaker to be on during dialing and off during handshake. ATM1 is the default setting, and the one that should be used in most applications.

Enable or Disable Recognition of Remote Digital Loop Signal &T

The modem has several self-test features (covered in Chapter 8). The tests are activated with different U commands, such as ATU1, and so forth. The &T command is a phone line conditioning command that enables or disables the modem’s ability to recognize the Remote Digital Loop (RDL) test signal.

The AT&T4 command lets the modem respond to a RDL signal, and places itself in digital loop. The AT&T5 command causes the modem to ignore the RDL signal. The factory default is &T5.

Enable/Disable Trelis Coded Modulation #T

This command enables or disables the Trellis Coded Modulation of the modem. There is usually no need to disable (turn off) Trellis codings except under an unusual line condition called impulse noise. AT#T0 turns Trellis coding off and AT#T1 turns Trellis coding on (factory default).

Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide

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Contents User Guide Patents User GuideRecord of Revisions Date Description TrademarksContents Registers Index 117Introduction and Description How To Use This Manual IntroductionModem Features 1 MT2834BA/BL Series Features Fax FeaturesTechnical Specifications Power Modem LED Indicators MT2834BA LED DisplayControls on PC Board Installation and Connection Safety Warnings What Is in Your Modem Package?Installation Installation ProcedureMultiModemBA Connections Installing PhoneTools, the Data Communications Software Is Your Modem Ready for Use?Software Configuration and Modem Basics Software Configuration Configuring Your SoftwareConfiguring Software for Your Modem PC Initialization StringsOther Parameters Changing Default ParametersConfiguring Software for Your Computer AT &F S0=0 &F9 &W0 CRAnswer/Originate Voice/Data Toggle Switch Modem BasicsSimple Operations Manual Dial and Automatic Answer Dialing/On-Line/Answering Manual Dial and Automatic AnswerManual Dial Backup Call Termination Dial Backup and Leased Line RestoralAutomatic Leased Line Restoral Operation Dial-Up Operation Manual Call OriginationAutomatic Answering Manual AnsweringAbort Timer Handshaking DetailsCall Termination Command Mode AT Command Editing Command ModeFunctional Modes Summary of AT Commands Functional ModesStore Modem Configure Data Result Codes Multi-Tech Result CodesStandard AT Result Codes Dialing Commands Dialing Action CommandsPulse or Tone Dial P T Dial Modifier CommandsVoice/Data Dialing $VD Set Pulse Dial Ratios &PAutomatic Pauses in Dialing Return to Command Mode After Dial Command ExecutionReverse the Mode of Operation R Long Space Disconnect YCalling Card Detect Tones $ Quiet Answer @Number Linking NN Phone Number Memory CommandsStoring Phone Numbers D...N Listing Numbers Stored in Memory LConfiguration and Default Storage Commands Loading Factory Defaults &FModem Reset Z Async/Sync Mode Switching &M Unix Uucp Spoofing $SPSynchronous Transmit Clock Select &X Result Codes Enable/Disable and No Response Answer Q Command Response Result Code CommandsEcho Command Mode Characters E Result Codes Multi-Tech or Standard AT &QResult Codes Basic and Extended and Call Progress Selection Guard Tones Not Used in BAI/BLI Models &G Phone Line Conditioning CommandsEnable/Disable Trelis Coded Modulation #T Bell/V.21 ToneCleardown at Disconnect &CD Fallback Modes When On-Line #FEnable/Disable Lowspeed Fast Connect $FC Auto Speed Detect #AData Terminal Ready Control &D 7 RS-232C Interface Control CommandsCarrier Detect Control &C CTS Control &RData Set Ready Control &S CTS/RTS Interaction Control &RFDSR/CD Interaction Control &SF Auto-Reliable Mode &E1 Error Correction CommandsNormal Mode &E0 Reliable Mode &E2Mode Select #L Auto-Reliable Buffering $AEnable/Disable Auto Reliable Fallback Character $F Error Correction/300bps $ERetransmit Count $R Flow Control Commands Hardware Flow Control &E4Xon/Xoff Flow Control &E5 Xon/Xoff Pass-Through &E7 Send Xon/Xoff Characters #XHewlett-Packard ENQ/ACK Pacing &E9 Maximum Block Size &BS Normal Mode Modem Flow Control On &E11Terminal/Computer Initiated Pacing &E13 Parity Selection #PNormal/Auto-Reliable/Reliable Mode Commands Xon/Xoff Pass-Through CommandsEnq/Ack Pacing Commands Speed Conversion Commands Speed Conversion $BAModem Baud Rate $MB Serial Port Baud Rate $SB Immediate Action Commands Listing On-Line Diagnostics L8 Off Hook HLine Probe Commands Force Answer Mode aExiting Command Mode, Going Back On-Line O Registers Escape Code Character Number of Rings Until Modem AnswersRings Which Have Occurred Return CharacterBackspace Character Time for Carrier Abort TimerLine Feed Character Wait Time for Dial ToneCarrier Detect Response Time S10 Carrier Loss Disconnect Delay TimeS13 Remote Configuration Escape Character S11 Tone Dialing Tone Spacing and DurationS16 Callback Attempts S15 Callback Time DelayS19 MT2834BL Only Dial-Back Timer S17 Changing Break TimeS24 PBX/CBX Disconnect Drop Time for DSR/CTS/CD S26 Failed Password AttemptsS29 Local Inactivity Timer S25 DTR Dropout TimeS36 Time Between DTR Inactive and Modem Off-Hook S30 Inactivity TimerS32 Time Elapse for Escape Sequence S37 Time Between DTR Active and Modem On-HookS48 Program V.34bis Connect Speeds Reading and Assigning S-Register Values Examples of Assigning ValuesExamples of Reading Values AT Command and S-Register Summary Callback Security and Remote Configuration Callback Feature Description Callback Security and Remote ConfigurationRemote Configuration Description To change your Remote Configuration feature statusTo set parity of the password/message prompt AT#CBN0xxxxxxxxxxCRCallback Operational Sequence Procedures Remote Configuration Procedures Remote Configuration Operation ProceduresRemote Configuration and Callback Security AT Commands Remote Configuration/Callback Security S-Registers DIP-Switch Settings Dip-Switch Settings MT2834BA PC BoardDIP-Switch Option Settings Switch #4 AS/400 Mode Synchronous Mode/Leased Line/Dial-UP = Down Down Dip-Switch Settings Speaker Volume Control Recording Option Configurations Switch Function Position EffectDIP Switches #13-14 DIP Switches #15-16 MT2834BADIP Switches #15-16 MT2834BL Warranty, Service and Tech Support Multi-Tech Systems, Inc. Warranty & Repairs Policies Warranty, Service, and Technical SupportOnline Warranty Registration Repair Procedures for International DistributorsInternet Sites Replacement PartsTechnical Support Country TelephoneAppendixes Upgrade Overview Appendix a Upgrading Your Modem’s FirmwareAppendix a Upgrading Your Modem’s Firmware Download the Upgrade File Upgrade the Modem’s Firmware Modem Does Not Respond to Commands Appendix B TroubleshootingNone of the LEDs Light When the Modem Is On Appendix B TroubleshootingAppendix B Troubleshooting Modem Dials But Cannot Make a Connection File Transfer Is Slower Than It Should Be Modem Cannot Connect When AnsweringModem Disconnects While On-line Am Losing DataAm Getting Garbage Characters on the Monitor Appendix C AT Command Summary Appendix C AT Command SummaryCommand Values Description DsNd Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 100$FCn MT2834BL Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 101$MBn Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 102$SBn Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 103Dial Tone Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 104Callback Security/Remote Configuration Command Summary Password Command Summary 25bis Commands25bis Operation Delayed and Forbidden NumbersAppendix D V.25bis Operation Appendix D V.25bis Operation25bis Set-Up and Initialization 25bis Mode AT Commands25bis DIP-Switches Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 108Change Serial Baud Rate CSP Command 25bis AT CommandsEnable/Disable V.25bis Mode $V Command 25bis Responses Result CodesListing Forbidden Phone Number RLF Command Dial Phone Number Provided CRN CommandListing Delayed Phone Numbers RLD Command Disregard or Connect to Incoming Calls DIC or CIC CommandITU V.25bis Country Specific Information Appendix D V.25bis Operation Belgium SingaporeMulti-Tech Systems, Inc. MT2834BA/BL Series User Guide 112 Appendix E MultiModemBA Cables Appendix E MultiModemBA/BL CablesAppendix F Regulatory Information FCC Part 68 TelecomFCC Part Canadian Limitations Notice Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 115South African Notice Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 116Appendix G Weee Statement Index Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 11791-116 Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 118PBX/CBX Disconnect Drop Time for DSR/CTS/CD63 Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide 119