Certain set of rules or in other words “Communicaion Protocol” is used to communicate on the Internet. Every protocol is defined and work for particular tasks, for example FTP for file transfer, SMTP for mail transfer, and HTTP for world wide web.

Session Initiation Protocol or SIP is a signaling protocol used for VoIP and other text and multimedia sessions like online games, instant messaging, videos etc. SIP works in conjunction with several other protocols that specify and carry the session media.

SIP features with almost all functionalities of Internet Telephony includes:

  • Call and Media transfer
  • Conferencing
  • Call Hold

In VoIP, there are a number of other protocols that can be used to communicate which includes the Session Initiation Protocol (SIP) and Inter-Asterisk eXchange (IAX2).