Editing Handshake (computing) (section)

=== Dial-up access modems ===
One classic example of handshaking is that of [[dial-up modem]]s, which typically negotiate communication parameters for a brief period when a connection is first established, and there after use those parameters to provide optimal information transfer over the channel as a function of its quality and capacity. The "squealing" (which is actually a sound that changes in pitch 100 times every second) noises made by some modems with speaker output immediately after a connection is established are in fact the sounds of modems at both ends engaging in a handshaking procedure; once the procedure is completed, the speaker might be silenced, depending on the settings of operating system or the application controlling the modem.