Day: 24 July 2016
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SIP Components
User Agents: End system acting on behalf of user e.g. client & server. Initiates SIP request & server receives requests and returns responses on behalf of user. Network Servers: Three types available: Registration server – receives client location updates. Proxy server – forwards receiving request to next-hop server. Redirect server – determines next-hop server, returns…
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SIP Functions
SIP has following functions: User Location: determination of end system to use for communications Call Setup: ringing & establishing call parameters by both called and calling parties User Availability: determination of willingness of called party to engage in communications User Capabilities: determination of media and media parameters to use Call Handling: transfer & termination of…
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Session Initiation Protocol (SIP)
Distributed architecture for creating, modifying and terminating sessions with one or more participants. Controls communications sessions. Standardised under IETF. Covers video conferencing, audio conferencing and one-to-one telephone calls. Stack independent, usually run over TCP or UDP. Uses request/response model similar to HTTP – client sends a request and gets a response from server. Requests/responses in…
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H.323
ITU-T’s (International Telecommunications Union) standard – vendors need to comply to supply VoIP. Encompasses point to point communications & multipoint conferences. Consists of four components: Terminals Endpoint host systems providing real time, two way comms. Can communicate with another H.323 terminal, H.323 gateway or MCU. Gateways Endpoint providing communication between terminal or another gateway. Translates…