Hi Kuldeep,
A handshake is the process by which two devices, such as modems, initiate communication with each other in order to establish a session, in which the devices can exchange any desired information.
This initial communication is necessary because the modems at each end of the line may have different capabilities (such as maximum data transfer speeds), and thus they need to inform each other of their respective capabilities (and settle on the highest transmission speed that both can use). Also, in the case of higher speeds, the modems have to determine the length of line delays so that their echo cancelers can be used properly.
Handshaking begins when one device sends a message to another device indicating that it wants to establish a communications channel. The two devices then send several messages back and forth that enable them to agree on a communications protocol.
Reagrds
