e value communicated by the ATGW entity (8899). 4) The SIP 183 Session Progress response from the domain HomeB. net contains the characteristics of the RTP stream in the SDP message body: - IPv4 address (200.2.2.2); - port number (6544). 5) Upon receipt of the provisional SIP 183 Session Progress response, the ATCF entity configures the ATGW entity and replaces the SDP message body received from the domain HomeB. net by that received from the ATGW entity: - the IP address (200.2.2.2) is replaced by the ATGW entity address (200.1.1.1); - the port number (6544) is replaced by the value communicated by the ATGW entity (11234). 9.2.2.3. Session establishment at terminating side The procedure for establishing the session implementing e-SRVCC function for an incoming call is illustrated in Figure 9.14. Service Centralization and Continuity P-CSCF SCC AS S-CSCF I-CSCF HomeA net DIAMETER LIR SIP INVITE DIAMETER LIA SIP 100 SIP INVITE SIP 100 SIP INVITE SIP 100 SIP INVITE SIP 100 SIP INVITE SIP 100 SIP INVITE SIP INVITE SIP 100 SIP 100 SIP 183 SIP 183 SIP 183 SIP 183 SIP 183 SIP 183 SIP 183 SIP PRACK SIP PRACK SIP PRACK SIP PRACK SIP PRACK SIP PRACK SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP UPDATE SIP UPDATE SIP UPDATE SIP UPDATE SIP UPDATE SIP UPDATE SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP 180 SIP 180 SIP 180 SIP 180 SIP 180 SIP 180 SIP 180 SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP 200 SIP ACK SIP ACK SIP ACK SIP ACK SIP ACK SIP ACK Figure 9.14. Session establishment for service continuity terminating side 1) The SIP INVITE request received from the domain HomeA. net by the I-CSCF entity contains the SDP message body with the RTP stream characteristics: - IPv4 address (200.1.1.2); - port number (8899). VoLTE and ViLTE 2) The S-CSCF entity forwards the SIP INVITE request to the SCC AS, ATCF, P-CSCF and Bob's UA entities: - the identity of the SCC AS entity is obtained following the review of the initial filter criteria (iFC); - the identities of the ATCF and P-CSCF entities are retrieved fr