Design and Implementation of Extended SIP Protocol-ed Instant Communication System

The instant communication software system has been seen as one of the most popular application system in nowadays.Most of the tradition instant communication system refer to a C/S architechture,and use their own communication protocol respectively.Moreover,the communication protocol should be modified when audio and video communication is needed.In this paper,a prototype instant communication system is proposed.It is based on the extended SIP protocol.The implementation of instant messaging under Linux programming environment is described.