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

Using the AT Command Set

This chapter includes information about


You can use AT commands to change your modem settings at any time.

To send AT commands to your modem, you need to put your communications software in Terminal Mode. In terminal mode, what you type is sent directly to the modem.

General rules for using AT commands:

  • You must follow some general guidelines to send AT commands to your modem:
  • Type AT before each command and press Enter after each command.

    Note: The exceptions are A/, A> and +++, which require neither AT nor Enter.

  • Leave zeroes off the end of AT commands. A missing numeric parameter is assumed to be a zero. For example, ATE is equivalent to ATE0.
  • Either use AT (all caps) or at. Mixed case, as in At for example, is unacceptable.
  • Create compound commands of up to 56 characters between AT and Enter.
    Example: AT&K3DT5551234
AT Attention; a command follows.
&K3 Disable MNP5 data compression; use only V.42 bis compression.
DT Dial the following number using tone dialing.

Note: Hyphens and parentheses add to the count of 56 characters but spaces do not.

Basic AT commands

The command AT informs the modem that a command is coming. AT must precede all commands except A/, A> and +++.

To configure your modem to
Re-execute the last-issued command.
Repeat the last-issued command until canceled by pressing any key.

Sending ATD5551234 will make the modem dial 555 1234. Now, if you send A/ the modem will dial 555 1234 again.


Using S-Registers

S-Registers are addresses of places in memory where various timing parameters, redefinitions of selected ASCII characters, and other configuration settings are stored.

Initially, the S-Register settings for each of the NVRAM templates are the same. You can overwrite an S-Register’s stored value. See the default values listed in the S-Registers chapter of the Appendixes section for a complete listing of the initial settings.

Displaying S-Register settings

You can display S-Registers in a variety of ways. See the table below for more information.

To display
Contents of ONE S-Register
ATSr?, where r is the register’s number
S-Register settings in the NVRAM template
S-Register settings in RAM (the current configuration)

Example: Sending ATS0?, displays the contents or setting for S-Register 0.

Note: When using the commands ATI4 and ATI5, S-Register settings appear as a table eight columns wide. Each entry of the form must be "Smm=nnn", where mm is a register number between 0 and 73 and nnn is a decimal value between 0 and 255.

Setting an S-Register

You can configure each S-Register setting manually.

CAUTION: If you do not write an S-Register setting with &W, the setting will be retained only until the next reset or power off.

To change Command
Settings for a register in the current configuration ATSr=n

Example: Sending ATS0=2, changes the setting for S-Register 0 to 2. This setting will cause the Courier 56K Business Modem to answer, in Auto Answer Mode, on the second ring.

Note: In the command ATSr=n, r is the register's number and n is a decimal value from 0-255 (unless otherwise indicated) that specifies the setting.

Getting a list of S-Registers

To display Command
A list of S-Registers ATS$

Note: In order to issue this command, you must be in Terminal Mode. Refer to the S-Registers chapter of the Appendixes section for a complete list of S-Registers.


Understanding bit-mapped S-Registers

A bit-mapped S-Register uses one number to describe a collection of settings. Bit-mapping allows you to pack a lot of information in a small space.

Bit-mapped registers are in the form of Sr.b=n, where r is the bit-mapped register; .b is the bit; n is 0 (off) or 1 (on).

Refer to the S-Registers chapter of the Appendixes section to see how bits are mapped into decimal values and for information about setting bit-mapped S-Registers.


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