SIP

Introduction

SIP offers the possibility of users to start communication and services form any location and for network to identify the users wherever they may be.

•SIP is a Session Initialization Protocol
•SIP is an application layer protocol
•It is a signaling protocol
•SIP is an alternative to H323 protocol – the video conference transmission protocol.
•It establishes, modifies, and terminates media session.

Applications supported by SIP

•Video Conferencing
•Internet telephony
•Distance learning
•Multimedia distribution

Strengths of SIP

•Simplicity
•Scalability
•Extensibility
•Modularity


Five Facets of SIP

•User Location – Where are the end users of the session present?
•User Capabilities- What should be the media of communication and media parameters ?
•User availability – whether the called party is available for a communication?
•Call Setup – Establishing a call.
•Modifying session parameters – Manages the call.

Components in SIP

•User agent server
–Server application that contacts the user when a SIP request is received.
•User agent Client
–Client application that initiates the request
•Proxy server
–Intermediate program that act both as server and client.
•Redirect server
–It does not accepts call or initiates requests. It maps the address to one or more address and returns these address to client
•Location server
–It accepts the register request and offer location services.

Other Protocols that are used with SIP

•RTPàReal time Transport Protocol
•RTSPàReal Time Streaming protocol
•MEGACOàMedia Gateway Access Control Protocol
•SDPàSession description Protocol
•RADIUS/ DIAMETER- Remote Authentication Dial In User Service
•RSVP/YESSIR- Reservation Protocol/Yet another Sender Session Internet Reservations
•LDAPàLightweight Directory Access Protocol