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The Proxy For Call Session Control Function (P-CSCF) is the first contact point within the IP Multimedia (IM) Core Network (CN) subsystem for subscribers in an IP Multimedia Subsystem (IMS) network. The SBC
may be deployed with many functions of a P-CSCF in an IMS network. A P-CSCF is allocated to the IMS terminal during IMS registration, and does not change for the duration of the registration. From a standards perspective, the P-CSCF behaves like a SIP Proxy. In other words, it accepts requests and services them internally or forwards them onwards. The figure below depicts the
in the role of a P-CSCF.
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- S-CSCF / I-CSCF over Mw interface (SIP)
- I-CSCF over Mw interface (SIP)
- IBCF over Mx interface (SIP)
- P-CSCF/A-SBC to MGCF over Mb interface (RTP/RTCP)
- PCRF over Rx interface (Diameter)
- DNS interface from P-CSCF to DNS server
- GM interface between UE and P-CSCF
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