Practical UNIX

An Overview of Modem Communications

Modems are telephones for computers. Like any standard telephone, they can handle both incoming and outgoing data to and from any location. Modems speak their own language, which computers understand but humans don’t. As such, when a modem dials a number, the call must be answered by another modem for any meaningful communication to occur. But telephones are like this, too. After all, what would be the point of making a telephone call to somebody who doesn’t speak the same language as you?

When two modems are connected, it becomes possible to enable effective communication between the two remote hosts operating the modems. Typically, this communication enables such things as file and printer resource sharing ...