SIP is a standard protocol that is required for initiating an interactive session for users and can include more than one element at a time such as video, voice and data. If you don't already know much about SIP or what the advantages are, then read on to know more.
The Session Initiation Protocol (SIP) is a new generation Internet Engineering Task Force(IETF) specified signaling protocol. It's widely used now a days owing to increased need of communication among communication providers, their partners and subscribers. SIP these days is used for controlling sessions like voice and video calls among others, over Internet Protocol (IP). Other examples of SIP operated applications include video conferencing, streaming multimedia distribution, instant messaging, presence information, file transfer and online games.
The result of an idea born in a computer laboratory almost a decade ago, SIP is world's first protocol that enables multi-user session regardless of media content. SIP also happens to be a major upgrade on previously available protocols like Media Gateway Control Protocol (MGCP). It shares at least three separate protocols when active, those being:
1. A protocol to set up the session between the participants,
2. Session Description Protocol (SDP), and
3. A suitable protocol that conveys information in the session.
All in all, any given communication SIP will make use of following components:
User Agent Client (UAC)
UAC is one side of double sided client components, the second side is known as User Agent Server (UAS). The UAC is capable of initiating up to six feasible SIP requests to a UAS which are INVITE, ACK, OPTIONS, BYE, CANCEL and REGISTER.
User Agent Server (UAS)
UAS is the server that is responsible for hosting applications responsible for receiving one of six SIP requests from UAC. Once the request is received, it is also responsible for sending a response back to UAC.
Proxy Server
In most cases proxy server acts as a mediator between UAC's and UAS's. It can also be used for name mapping.
Redirect Server
This server allows the redirection, which in simple term means that enabled users will still be available for contact via same SIP identity, even though they have changed their geographical location.
Registrar Server
The registrar server allows the users to change the address in which they were previously contactable. New address then provided, is recorded by this server.
Using SIP has its own share of advantages. Some of those are listed below:
* SIP is very easy to understand just like Internet and so is its implementation. Being a part of IETF specification, it is required to have open-standards, so commonly associated with messaging over Internet.
* User over SIP is free to locate and contact each other regardless of number of participants and type of media content.
* Since there is no need to define the type of session, SIP comes with flexibility in terms of usage when it comes to number and type of services and applications.
* SIP also gives freedom to service providers, when it comes to choosing among various standard based components, giving them ability to harness new technologies.
