Mac OS X: How to Use Modem AT Commands

You can troubleshoot a modem in Mac OS X using AT commands. This document describes how.

This article has been archived and is no longer updated by Apple.

AT commands make a modem perform certain actions, such as dialing a phone number. Most of these command start with the letters "AT," which is short for "attention". If your modem manufacturer or Internet service provider (ISP) asks you to type AT commands to troubleshoot your modem hardware or your connection, follow these steps to issue the command:

Note: This document does not include the specific commands. Use commands provided by your Internet service provider or modem manufacturer for troubleshooting.

    1. Open System Preferences.
    2. Click Network.
    3. Choose Internal Modem from the Show pop-up menu, or choose the external port to which the modem is connected.
    Note: This menu is named "Configure" in Mac OS X versions 10.0 to 10.0.4.
    4. Click the PPP Tab.
    5. Click PPP Options.
    6. Click the checkbox to enable the "Connect using a Terminal window" option.
    7. Click OK.
    8. Click the Modem tab.
    9. Choose any modem script that starts with the words "Null Modem, such as Null Modem 19200" from the Modem pop-up menu.
    10. Click Apply Now.
    Note: This button is called Save in Mac OS X versions 10.0 to 10.0.4.
    11. Open the Internet Connect application.
    12. Click Connect. After several seconds, a Terminal window opens. At this point, the modem has not dialed.
    13. Type the commands that you were given. When you have finished, click Cancel to end the session, or click Continue to use a connection that you made.


For information about AT commands in Mac OS 9, see technical document TA21981: "Remote Access: Using the Terminal Window to Send AT Commands".

Published Date: Feb 20, 2012