is it possible to call Computer A with Computer B in Same Country via theirs dial up modems? i mean use computer as telephone (with Dial Up modem) i no need transferring voice just : 1) Computer A Dialing Computer B (with the Phone number) 2) Computer B is see that computer A is calling. 3) Computer B Answer.
please putting sample code or link for more information. if there is any library exist that made my work easier introduce to me. i don't want to involving with AT Commands. does this library help me? Have I Use TAPI? thanks.
Yes. As long as both computers have compatible modems. You'll need terminal software for both computers (probably hyperterm for WinXP, but it's been a while, so I can't say for sure). Basically, you'll need to have one computer call the other computer sending a string like "ATDxxxxxxx" where xxxxxxx is the phone number of the receiving computer. When the line starts ringing on the receiver, type "ATA" on the receiving computer to tell the modem to answer. After the handshake you should get a "CONNECT" message. Mind you, all this is subject to individual quirks of the modems and my memory, as it's been at least 8 years since I've done any work with dial up at all. But it should give you the basic idea.
来源：https://stackoverflow.com/questions/3697835/call-a-computer-with-another-computer-dial-up-modem