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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

Working with Memory

This chapter contains information about:

You can upgrade the software held in Flash memory by performing a software download. Refer to the Upgrading your Modem chapter of this guide for more information about performing a software download.


Courier 56K Business Modems contain three types of memory that you can interact with: random access memory (RAM), nonvolatile random access memory (NVRAM), and Flash memory.

Memory type
Applies to
Loss of power will
The current settings. Cancel any changes you make. To save settings before resetting the modem, use &W. See Working with RAM in this section for more detailed information.
Saved settings (any configurations you can store, retrieve, and change). NOT affect your settings.
Three templates of permanent settings (the Courier 56K Business Modem’s operating software).

NOT affect your settings.

You can retrieve the permanent settings, and save them to NVRAM, but you cannot alter them.

Not applicable.

Example: Sending ATI5 will display NVRAM settings on your screen.

Note: To see a complete listing of the permanent settings stored in Flash memory refer to the Flow Control Template appendix in this guide.

Working with RAM and NVRAM

You can change any setting just for the current session. For example, setting your Courier 56K Business Modem to AT&N8 will only allow a connection to a remote devices at a rate of 14400 bps or lower until the modem is reset. Once the modem is reset, the default variable connection rate will be re-established.

If you want the new setting to be a default, write it to NVRAM at the same time. From the example above, you would send AT&N8&W to the modem. The new default setting for your Courier 56K Business Modem will only allow a 14400 bps connection to a remote device.

Note: To restore NVRAM factory defaults, use the AT&Fn command. Refer to the Alphabetic Command Summary chapter of the Appendixes section for more information on setting &Fn.

Saving a Phone Number to NVRAM


For your modem to
Write the phone number(s) to a position(n) in memory. You can store up to 10 phone numbers of up to 40 characters each in positions 0-9.
Display the number stored in the last-dialed number buffer.
Display the phone number stored in NVRAM at position n, where n = 0-9.

CAUTION: Do not include modem commands in AT&Zn=s. Only dial commands and numbers can be stored.

Example: To store the phone number 555 6789 at position 2, type AT&Z2=5556789. If you want to dial the phone number you saved, type ATDS2.

If the call requires a special setting, insert it in the command before the DSn command. In this example, &M0 (no error control) comes before DS2. Type: AT&M0DS2

CAUTION: The AT&Zn=s command functions differently when Dial Security is enabled. Refer to the Dial Security chapter of this guide for more information.

Displaying S-Register Value Information

For your modem to
View the contents of a particular S-Register
(where r is the number of the S-Register)

Example: Sending ATS0? will allow you to view the contents of Register S0.

Saving a Command String to NVRAM

For your modem to
Store a command string in NVRAM. The command string can be up to 30 characters long; spaces do not count. This command is used so that you can call another modem without loading your communications software.

Display the stored command string

Once the command is stored, you can program the voice/data switch to send the stored command when pressed. Refer to the S-Registers appendix in this guide for more information about S-Register 32 and assigning voice/data switch functions.

Programming the Voice/Data switch

After storing a command to NVRAM, you can program the voice/data switch to execute the stored command string when pressed. The function of the voice/data switch is determined by the setting of S-Register 32.

  1. Open your communications software program.
  2. Store a command to NVRAM using the AT&ZC=string command (see the table above).
  3. Send ATS32=9 to your modem. This command will set the voice/data switch function to execute the stored command string.

    Note: You can reset the voice/data switch at any time (Refer to the S-Registers appendix in this guide for a complete list of S32 voice/data switch functions). You can also overwrite the stored command string with a new one at any time.

  4. Now, you can press the voice/data switch whenever you want the stored command string executed.

Example: Issuing AT&ZC=I6 to your modem stores the command string that displays the link diagnostic screen to NVRAM. Then issuing the ATS32=9 command to your modem will allow you to display the link diagnostic screen whenever the voice/data switch is pressed.


Working with Flash Memory

The Courier 56K Business Modem permanently stores three configuration "templates," or prepared sets of commands, in Flash memory. You can use the &Fn command to load one of the three configuration templates from Flash memory into current memory.

To load this configuration template into current memory
No flow control (low performance).
Hardware flow control.
Software flow control.

Example: Sending AT&F1 to your modem will load the Hardware Flow Control Template into RAM Memory.

DIP switch settings override AT commands at power-on. You can set DIP switch 10 to ON and reset the Courier 56K Business Modem to load the &F0 settings.

All of the settings in each template are given in the Flow Control Template appendix in this guide.

For more information about hardware and software flow control, refer to the Flow Control Template appendix in this guide.

Saving Flash Templates to NVRAM

To save one of the three flash templates to NVRAM and have it serve as the reset default, enter AT&Fn&W.

DIP switch settings override AT commands at power on. Make sure DIP switch 10 is OFF, or the &F0 template will be loaded.

Default Settings

When the Courier 56K Business Modem is turned on, it loads the settings stored in NVRAM. By default, these settings are the same as the &F1 template.

You can save any of the three templates, or save modified versions of them, in NVRAM for use as power-on defaults.

For your modem to
Display NVRAM settings (&F1 settings)
Substitute a template (other than &F1)
Save modified versions of the settings to NVRAM

Refer to the Flow Control Template appendix in this guide for a complete listing of the default values.