Connecting to your ISP

Using the AT Command Set

Upgrading your Modem

Modes of Operation

Dialing, Answering, and Hanging Up

Working with Memory

Controlling Result Code Displays

Controlling EIA-232 Signaling

Accessing and Configuring the Courier 56K Corporate 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


Courier 56K Corporate Modem Command Reference

Accessing and Configuring the Courier 56K Corporate Modem remotely

This chapter contains information about:


You can set up the Courier 56K Corporate modem so other devices can view or change its configuration remotely.

You should be familiar with these terms before you continue:

Local The device that is directly connected to the computer you are using.
Remote The device at the other end of a telephone connection.
Host The Courier 56K Corporate modem that will be accessed and controlled by other devices.
Guest The device that will access and control the host Courier 56K Corporate modem.


Setting Up Remote Access

At the Host Courier 56K Corporate Modem

  1. Prepare to send AT commands by putting your communications software in Terminal Mode.
  2. Enable remote access.

    Set Register S41 for a value of 1 or greater. S41 sets the number of login attempts available to the remote user. A setting of zero allows no login attempts disabling remote access.

    Example: Sending ATS41=1&W allows for 1 login attempt by a remote user.

    Note: This method will not work if the Courier 56K Corporate modem is attached to certain synchronous devices. Refer to the Dedicated/Lease Line and Synchronous Applications chapter in this guide.

  3. Set one or two remote-access passwords.

    You can set two passwords to allow different levels of access to each Courier 56K Corporate modem.
To allow guest users to
Use this command to assign a remote-access password
View the Courier 56K Corporate modem’s configuration.
View and change the Courier 56K Corporate modem’s configuration.

Example: Sending AT%P1= wombat will allow a remote user to log in with the password "wombat." The user can view and change the Courier 56K Corporate modem’s configuration.

Note: Remote-access passwords can be up to eight alphanumeric characters long, and are not case-sensitive.

Other Remote-Access Commands

The table below is a list of remote-access configuration commands.

For your modem to

Display a view-only password
Display a view-and-change password
Erase a view-only password
Erase a view-and-change password
Disable remote access entirely

Example: Sending AT%P1= will erase the view and change password.

WARNING: If you erase the %P1 password without disabling remote access (using ATS41=0), anyone could access the Courier 56K Corporate modem and change its configuration.


Accessing The Host

At the Guest Device

The guest device requires no configuration to access the host. Follow these steps:

  1. Be sure that the host device has enabled remote access and is set to auto-answer (ATS0=1). Know the password, if you will need one.
  2. Call the host device (although it doesn’t matter which device originates the call).
  3. After a connection is established, do this:

    Pause 4 seconds.
    Type 4 tildes: ~~~~
    Pause 4 seconds.

    Note: The administrator of the host device can change the remote-access character using S-Register 42, and the pause duration using S-Register 43. Refer to the S-Registers chapter of the Appendixes section for more information.

  4. You should see a display similar to this:

    USRobotics Courier 56K Corporate Remote Access Session
    Serial Number 000000A000000001

    Password (Ctrl-C to cancel)?

    There is a three minute time limit for entering the password. If the number of unsuccessful login attempts exceeds the set limit, the host device returns online and refuses any further login attempts during the remainder of the connection.

    When the host accepts the password, the following message and prompt will appear on your screen:

    Remote Access granted


    Note: You may not be prompted for a password. If you aren’t, password security is not active. The following prompt appears on your screen after you type the four tildes:

    Remote Access granted (query only)


    Note: During a remote-access session, the maximum number of characters between carriage returns is 40.


Viewing and Changing the Host’s Configuration

Once you've gained guest access to a host, you can communicate with the host just as if you were entering commands from its attached computer.

Depending on your access privileges, you can use the regular set of Courier 56K Corporate modem AT commands.

If you have this access privilege
You can use
Any of the inquiry (ATI) commands
View and Configure
Any of the Courier 56K Corporate modem commands, except those that cannot be used while online (for example, ATD or ATA). You can also use remote configuration commands.
See the next section for examples.

CAUTION: Be careful not to send ATZ or ATZ! or you will lose the connection!


Remote Configuration Commands

There are special commands that can be used only during a remote-access session.

You can change the host Courier 56K Corporate modem’s serial port rate by using the AT%Bn command.

To change the host Courier 56K Corporate modem’s serial port rate to
To change the host Courier 56K Corporate modem’s serial port rate to
110 bps
9600 bps
300 bps
19200 bps
600 bps
38400 bps
1200 bps
57600 bps
2400 bps
115200 bps
4800 bps

Example: Sending AT%B6 will change the Courier 56K Corporate modem’s serial port rate to 9600 bps.

You can use the AT%Fn command to control the data format.

To change the data format to

No Parity (8 data bits)
Mark parity (7 data bits)
Odd Parity (7 data bits)
Even parity (7 data bits)

You can use the AT%Cn command to control whether and when to apply changes to the configuration.

For your modem to
Defer configuration changes to when the call ends.
AT%C0 (Default)

Restore the original configuration.

Use this command to cancel any changes made during remote access and restore the original configuration.


Force configuration changes.

Use this command to make configuration changes take effect immediately. We do not recommend forcing changes unless it is absolutely necessary because an unreliable connection, or even a loss of connection, may result.


Example: Sending AT%C1 will cancel any changes made to the modem during a remote access session and restore it to the original configuration.

Note: Even though, by default (%C0), the changes you make do not take effect until the next connection, the new configuration is reflected immediately in inquiry responses (ATIn). Commands that have been written to NVRAM (using &W) and forced configuration changes (%C2) will not be restored to their previous settings when you send the host AT%C1.

After you make changes to the host’s configuration, the remote- access prompt changes from Remote-> to Remote+>.

If you restore the original configuration using the AT%C1 command, the first prompt is restored, assuring you the original configuration is intact.


Quitting A Remote Access Session

If you want to quit the remote access login before you have entered the password, return online by pressing <Ctrl>C or typing ATO.

After you’ve entered the password, you can quit by sending one of these commands:

To end the remote-access session
And keep the connection.
And end the connection.
End the connection, and reset the host modem.

Note: Before you disconnect, issue the ATI5 command to the remote modem and check its S41 setting. Make sure S41 is set for a value of 1 or greater. If S41 is set to 0, when you disconnect you will not be able to access the remote modem again. To prevent this send ATS41=1&W before you disconnect.