SIP – A protocol that allows voice, data, fax, video, instant messaging and even online gaming to be integrated with web-based applications. The session initiation protocol (SIP) is emerging as the favored standard for setting up, modifying and terminating telephone calls over the internet. Its main things on the fly-in the hands of the user. The Session Initiation Protocol (SIP) is an application –layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants. These sessions include internet multimedia conferences, Internet telephone calls and multimedia distribution. A multimedia session is a set of multimedia senders and receivers and the data streams flowing from senders to receivers. Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these.