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Session Initiation Protocol (SIP)

SIP is a lightweight, transport-independent, text-based protocol. SIP has the following features: Lightweight, in that SIP has only four methods, reducing complexity Transport-independent, because SIP can be used with UDP, TCP, ATM & so on. Text-based, allowing for low overhead SIP is primarily used for VOIP calls | Session Initiation Protocol (SIP) Features of SIP SIP is a lightweight, transport-independent, text-based protocol. SIP has the following features: Lightweight, in that SIP has only four methods, reducing complexity Transport-independent, because SIP can be used with UDP, TCP, ATM & so on. Text-based, allowing for low overhead SIP is primarily used for VOIP calls Functions of SIP Location of an end point Signal of a desire to communicate Negotiation of session parameters to establish the session And teardown of the session once established. How SIP works SIP user agents: like cell phones, PCs etc. They initiate message writing. SIP Registrar servers: They are databases containing User Agent locations; they send agents IP address information to SIP proxy servers. SIP Proxy servers: accepts session request made by UA and queries SIP registrar server to find recipient UA address. SIP Redirect servers: they help communicating outside the domain Continued Continued Our user A tries to | Session Initiation Protocol (SIP) Features of SIP SIP is a lightweight, transport-independent, text-based protocol. SIP has the following features: Lightweight, in that SIP has only four methods, reducing complexity Transport-independent, because SIP can be used with UDP, TCP, ATM & so on. Text-based, allowing for low overhead SIP is primarily used for VOIP calls Functions of SIP Location of an end point Signal of a desire to communicate Negotiation of session parameters to establish the session And teardown of the session once established. How SIP works SIP user agents: like cell phones, PCs etc. They initiate message writing. SIP Registrar servers: They are databases containing User Agent locations; they send agents IP address information to SIP proxy servers. SIP Proxy servers: accepts session request made by UA and queries SIP registrar server to find recipient UA address. SIP Redirect servers: they help communicating outside the domain Continued Continued Our user A tries to call user B (1) Domain SIP proxy server now queries Registrar server in the same domain to know about user B’s address (2) Registrar responds with the address (3) SIP proxy server calls B (4) User B responds to SIP proxy (5) SIP proxy answers to User A (6) Now multimedia session is established on RTP protocol (7) More about SIP SIP relies on SDP and RTP protocols SIP proxy is a server in a SIP-based IP telephony environment The SIP proxy takes over call control from the terminals and serves as a central repository for address translation (name to IP address) SIP Advantages SIP is a based on HTTP and MIME, which makes it suitable for integrated voice-data applications SIP is designed for real time transmission SIP Advantages Uses fewer resources Is Less complex than H.323 protocol SIP uses URLs and is human readable SIP Disadvantages First one: 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 .