VoLTE IMS Protocols
In IMS subsystem, the critical protocols are the Session Initiation Protocol (SIP), SigComp, Real-time Transport Protocol (RTP), RTP Control Protocol (RTCP) and IP Security (IPSec) and Diameter. These protocols are very important because these are the ones impacted by the UE or have direct impact on UE operation.
In a VoLTE call SIP protocol is used to create, modify and terminate sessions, essentially negotiating a session between two users. SIP does not perform transport layer (delivering data) those are done by RTP/RTCP.
SIP is a sequential protocol with request/response similar to HTTP both in functionality and format. Every SIP request begins with a starting line that includes the name of request type and also called as method.
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