Sign in with Microsoft
Sign in or create an account.
Hello,
Select a different account.
You have multiple accounts
Choose the account you want to sign in with.

3.00 3.00a 3.10 3.11
WINDOWS
kbtshoot kbtlc

Summary

When you troubleshoot communications problems in Windows, an MS-DOS-level communications program is often required to test the modem and ports outside of Windows.


If an MS-DOS-based application cannot be used, it is possible to test the modem connections by typing the following command at the MS-DOS command prompt

Echo ATDT > ComX
where X is the number of the serial port the modem is connected to or emulating.


The modem should respond with a dial-tone or just a communication signal.

More Information

The ATDT command is a signal to the modem that is interpreted as Attention Dial Tone. The first command, Attention, signals to the modem that it is about to receive information, and the Dial Tone command instructs the modem to enable a line to dial out.


NOTE: The modem may not always give a dial tone with this test procedure because a number does not follow the command; however, the modem should give some kind of signal that information was received.

Need more help?

Want more options?

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.

Was this information helpful?

What affected your experience?
By pressing submit, your feedback will be used to improve Microsoft products and services. Your IT admin will be able to collect this data. Privacy Statement.

Thank you for your feedback!

×