In Windows XP/2000:
Go to Start > Control Panel > Phone and Modem Options >Modems > select your modem > Properties > Diagnostics.Click on Query Modem button.

In Windows 95/98/ME:
Go to Start > Settings > Control Panel > Modems >Diagnostics tab
You should see a new modem installed on one of the COM ports (eg.COM3).
Select the COM port with your modem, Click on "More Info..."button.

After a while, you will see a window with the response from themodem.
If you are getting "Port already opened" message, you need todisable software which may use the COM port of the modem (e.g.faxing software) and reboot computer. If you are getting an errorabout modem not responding, try to reinstall the modem's driver.