Product Features

Installing Your Modem

Using the AT Command Set

Upgrading your Modem

Modes of Operation

Dialing, Answering, and Hanging Up

Configuring with DIP Switches

Working with Memory

Controlling Result Code Displays

Controlling EIA-232 Signaling

Accessing and Configuring the Courier 56K Business Modem Remotely

Controlling Data Rates

Dial Security

Flow Control

Handshaking, Error Control, Data Compression, and Throughput

Displaying Querying and Help Screens

Testing the Connection

Dedicated/Lease Line and Synchronous Applications




Alphabetic Command Summary

Flow Control Template

Result Code Meanings and Sets

Technical Information

V.25 bis Reference


Fax Information for Programmers

Viewing LEDs

Regulatory Information and Limited Warranty


Courier 56K Business Modem Command Reference

Technical Information

Your modem uses multiple standard data communications protocols and is also compatible with many nonstandard schemes. The following schemes are supported:



This modulation
V.90 and V.92 ITU 56K standard, server capabilities. 56 through 28 kbps; Pulse Coded Modulation (PCM).
ITU-T V.34 33.6/31.2/28.8/26.4/24/21.6/19.2/16.8/14.4/12 kbps; 9600/7200/4800 bps asynchronous Trellis Coded Modulation (TCM)
V.FC 28.8/26.4/24/21.6/19.2/16.8/14.4 kbps asynchronous TCM
V.32 terbo 21.6/19.2/16.8/14.4/12 kbps; 9600/7200 bps asynchronous TCM; 4800 bps asynchronous Quadrature Amplitude Modulation (QAM)
16.8/14.4/12 kbps; 9600/7200 bps asynchronous, asymmetrical, 450 bps back channel with automatic handshake adjustment to 300 bps TCM and QAM; 4800 bps asynchronous, asymmetrical, 450 bps back channel with automatic handshake adjustment to 300 bps QAM.
ITU-T V.32 bis 14.4/12 kbps; 9600/7200 bps asynchronous TCM; 4800 bps asynchronous QAM
ITU-T V.32 9600 bps asynchronous, TCM; 4800 bps asynchronous, QAM
ITU-T V.22 bis 2400 bps asynchronous, QAM
Bell 212A 1200 bps (also V.22) asynchronous, Differential Phase Shift Keying (DPSK)
ITU-T V.23 1200 bps asymmetrical with 75 bps back channel with Frequency Shift Keying (FSK), used by some U.K. and European phone systems.
Bell 103
300 bps (ITU-T V.21 optional) asynchronous, Frequency Shift Keying (FSK)


Error Control, Data Compression, Testing, and Dialing

This modulation
ITU-T V.42 LAPM error control, 1200 bps and higher
MNP Levels 2, 3 and 4 error control, level 5 data compression, 1200 bps and higher
Asymmetrical mode, at 16.8/14.4/12 kbps; 9600/ 7200/4800 bps, 450/300 bps back channel
ITU-T V.42 bis Data compression, 1200 bps and higher
ITU-T V.54 Digital and remote digital loopback testing
ITU-T V.25 bis
Dialing and answering method for automatic calling and/or answering equipment




Your Courier 56K Business Modem provides Group III -compatibility when controlled by Class 1 or Class 2.0 fax software. In addition, your Courier 56K Business Modem adheres to the following standards:

This modulation
TIA/EIA-578 Service Class 1 Asynchronous Facsimile DCE Control Standard

Service Class 2.0 Asynchronous Facsimile DCE Control Standard
ITU-T V.17 14.4/12 kbps
ITU-T V.29 9600/7200 bps
ITU-T V.27 ter 4800/2400 bps
ITU-T V.21 300 bps





This feature

Supported serial port rates
230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200, and 300 bps
Adaptive Speed Leveling (ASL) 21600, 19200, 16800, 14400, 12000, 9600, 7200, and 4800 bps
Serial port connector DB-25

Communications channel
Full- or half- duplex on 2-wire phone lines; demand-driven high-speed turnaround in HST mode; symmestrical speeds in V.32 bis.
Data format Binary, serial; defaults to 8-bit word length, no parity, and 1 stop bit.
Word Length
Parity (1 Bit)
Stop Bits
Even, odd, mark, space
Flow Control Buffers Variable sizes
Command Buffer 56 characters, excluding the AT prefix, Carriage Return, and spaces
Test Options Remote digital loopback, digital loopback, test pattern, and dial test
Failed Call Timeout 60 second default, programmable 2-255 sec.
Answer Tone Timeout 60 seconds
Answer Tone Detector 2080-2120 Hz
Loss of Carrier (Disconnect Timer) 0.7 second default, programmable 0.2-25.5 sec.
Equalization Adaptive
Receive Sensitivity - 43 dBm + 2 dBm
Transmit Level - 9 dBm maximum
Transmitter Frequency Tolerance .01%
Certification FCC 15, EN55022 (CISPR 22), ICES-003, AS/NZS3548, VCCI; Class B; EN50082-1; UL/C-UL, IEC 950, EN60950, TS001; FCC 68, CTR 21

Ringer equivalence



Serial Ports

Most computers provide a DB-25 or DB-9 port that conforms to the EIA-232 standard.


The EIA-232 Interface

Your modem’s serial port is factory set to signal according to the EIA-232 standard.




Wiring a DB-25 to DB-9 Cable

DB-9 connectors for PCs should be wired at the computer end of the cable as shown below.



Minimum Requirements

Some computer/terminal equipment supports only a few of your modem’s EIA-232 signals. The minimum required for your modem to operate asynchronously follows:

DB-25 DB-9 Supports this signal
Pin Pin Function
2 3 Transmitted Data
3 2 Received Data
7 5 Signal Ground
20 4 Data Terminal Ready


Flow Control Requirements

If your computer and software support Clear to Send and you wish to use Transmit Data hardware flow control (&H1), Pin 5 (DB-25) or Pin 8 (DB-9) is required.

If your computer and software support Request to Send and you wish to use Received Data hardware flow control (&R2), Pin 4 (DB-25) or Pin 7 (DB-9) is required.



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