Session initiation-protocol

1. Session-Initiation-Protocol PRESENTED BY S.SANTHOSH 12G21D5830

2. ABSTRACT SIP provides for the seamless transmission of voice, fax, and data across IP and traditional telephone networks. The IETF defines SIP as “a text- based protocol, similar to HTTP and SMTP, for initiating interactive communication sessions between users. Such sessions include voice, video, chat, interactive games, and virtual reality.” The Session Initiation Protocol (SIP) is an Internet Engineering Task Force (IETF) standard protocol for initiating an interactive user session that involves multimedia elements such as video, voice, chat, gaming, and virtual reality.

3. INTRODUCTION SIP is a request-response protocol, dealing with requests from clients and responses from servers. Participants are identified by SIP URLs. Requests can be sent through any transport protocol, such as UDP , SCTP, or TCP.  The protocol can also invite participants to unicast or multicast sessions that do not necessarily involve the initiator. Because the SIP supports name mapping and redirection services, it makes it possible for users to initiate and receive communications and services from any location, and for networks to identify the users wherever they are .

4. APPLICATIONS It has given rise to generation of new types of smart phone. With the help of the technology now smart phones also support the video conferencing. setting up voice-over-IP calls setting up multimedia conferences event notification (subscribe/notify) à IM and presence text and general messaging signaling transport

5. FUNCTIONALITY As the name implies the session initiation protocol is about initiation interactive communications sessions between users. SIP also handles termination and modifications of sessions as well. Locating the user – supports personals mobility Inviting the user for session Delivering the session description Terminate the session

6. ARCHITECTURE

7. WORKING PROCESS User Agents: User agent is an application which contains both a user agent client and user agent server. A user agent client (UAC) is a client application that initiates the SIP request. A user agent server (UAS) is a server application that contacts the user when a SIP request is received. proxy server: The Proxy Servers are application layer routers that forward SIP request & responses.

8. Continution Redirect server : A redirect server is a server that accepts a SIP Requests & then return the location of another SIP user agent & server where the user might be found. Registrar server : A registrar is a server that accepts REGISTER requests. A registrarer is typically co-located with a proxy or redirect server and offer location services .

9. ADVANTAGES SIP is scalable, easy to implement, and requires less setup time than its predecessor protocols. SIP can be used to modify any session in progress, a normal telephone call session can be converted into a multi-party videoconference. Users can join in the session no matter what kind of terminal he is using or where he is located. The other person may be logged on to Internet through a PC, or may be traveling with a cell phone .

10. DISADVANTAGES One SIP challenge is that SIP message contain information that Client and/or server will like to keep private but SIP header as well as message in the open and distributed architecture of VOIP systems makes it difficult to keep this information confidential. When a SIP user is registering with SIP Registrar server the attacker can hijack the registration. Two main reasons for this attack are: SIP messages being sent in clear and no SIP message authentication built into the protocol

11. CONCLUSION SIP is now a days used for internet conferences, internet multimedia, internet telephony calls at distance learning with compatible session like voice, chat , traditional telephony networks, voice, fax, interactive games etc. SIP become a standard IETF protocol for signaling in third – generation mobile networking SIP runs on top of several different transport protocols.

12. THANK YOU