A modem allows a point-to-point data link to be carried over the
analog telephone system (PSTN, also called POTS, or Plain Old
Telephone System), thus:
The modem can:
Dial the telephone number of another modem under program
control, or answer the phone.
Negotiate a connection at the highest common bit rate that each
modem can support -- current maximum is 56kbps.
perform"on the fly" data compression, giving higher "apparent"
data rate.
perform (under some conditions) error detection and correction
-- able to recover from some line errors due to noise, etc.
