互联网工作原理(14.Modem是如何工作的)

 

Modems are controlled by software on your PC using a language called the Hayes command set or AT command set. When a modem is to be dialed, the first command given it is to tell it to go off hookin other words, to open a connection with the phone line. After that, a command tells the modem to dial a telephone number to make a connection.