The software modem in current notebook computers are partially powered from the telephone line. In the past, one way to tell if the modem was partly functional was to type ata[cr] and listen to the answer tones and attempt to negotiate a connection. These modems will not respond with any sounds if not connected to the line, and after a timeout period return a NO CARRIER message.

This does not mean that the modem is not working. Always check to see that the line is connected. Also, if the line is connected and the ata command does produce dial tone and answer tones, then the connection might be to a digital PBX, or not be able to supply the proper amount of current to the modem’s DAA.