VoNR call procedures
This section evaluates the activities that need to take place to ultimately set up a VoNR call.
High-level call procedure activities
Key procedures take place within the 5G system, IMS, and policy charging control elements such as PCF to make a VoNR call. There is activity taking place with the SIP and the IMS. There is also activity taking place with the Diameter protocol and PCF. Moreover, there is also activity taking place in the 5G access network itself. Hence, these three network domains work together to establish a VoNR call.
To go into this in more detail, the process starts with the concept of exchanging the Session Description Protocol (SDP) messages: SDP Offer and SDP Answer. A flow of VoIP packets is required between two parties in a VoIP call. Therefore, the IP address and ports between the two parties should be known. Moreover, the voice codec and required bandwidth that need to be used should also be known. The SIP doesn’t do this...
