SIP Definition

Session Initiation Protocol (SIP) is responsible for connecting, monitoring and disconnecting VoIP sessions.

12:51 10 June 2017

Session Initiation Protocol (SIP) refers to the hardware/software combination that allows you to make free calls using the Internet. It is an IP telephony signaling protocol used by your Internet service provider (ISP) to integrate basic IP phone capabilities with online chat, web and email. SIP proxy servers can also provide advanced call-processing functions such as call routing, authentication and security.

 

In addition to establishing sessions for real-time sessions, SIP server also supports traditional telephony features such as call forwarding, time-of-day routing and personal mobility. However, SIP is mostly used to start and end VoIP phone calls. In a typical SIP session, the client, which is recognised using their SIP address, requests for a voice connection with a SIP server using a device (a computer, tablet or smartphone). The SIP server then responds to tell the client whether or not a voice connection is possible.

 

Some of the SIP clients that you may be familiar with are Microsoft MSN Messenger and Apple iChat. These are instant messaging applications that allow you to send out voice and video messages for free as long as you have a reliable Internet connection.