=IN IP4 192.0.2.1 m=audio 49170 RTP/AVP 96 97 a=visited-realm: Va.operatorV. net IN IP4 192.0.2.1 49170 . . . 8) The TRF entity performs ENUM resolution on the URI identity of the destination to which it adds the iotl parameter indicating the direction of the request (visitedA-homeB), withdraws its URI identity in the Route header and transfers the SIP INVITE request to the IBCF-5 instance. INVITE SIP: <sip:+46107197378@operatorY;user=phone;iotl=visitedA- homeB> SIP/2.0 Feature-Caps:*;+g.3gpp.loopback=<"homenetwork-A"> Content-Type: application/sdp Content-Length: (...) C=IN IP4 192.0.2.1 m=audio 49170 RTP/AVP 96 97 . . . a=visited-realm: Va. operatorV . net IN IP4 192.0.2.1 49170 Roaming 241 When the IBCF-5 instance received the SIP INVITE request, it generates a new request to the SIP INVITE Bob's home network. 9) Upon receipt of the SIP 183 Session Progress message from Bob's home network, the IBCF-5 instance generates to the TRF entity, the SIP 183 Session Progress message, whose associated SDP message contains RTP stream characteristics reported by the TrGW-1 entity. The SIP message also contains the instance 1 of the header a=visited-realm populated with the domain name to which the IBCF-5 instance is connected the IP address and the RTP stream port number of the TrGW-1 entity. SIP/2.0 183 Session Progress Content-Type application/sdp Content-Length: (...) C=IN IP4 192.0.2.4 m=audio 16511 RTP/AVP 97 98 a=visited-realm: Va. operatorV.net IN IP4 192.0.2.4 16511 The SIP 183 Session Progress message is forwarded without changing the SDP message to the IBCF-4 instance. 10) The IBCF-4 instance transfers to the IBCF entity of the visited network (IBCF-3 instance), the SIP 183 Session Progress message whose SDP message replaces the IP address of the RTP stream of the IBCF-5 instance by 0.0.0.0 value. SIP/2.0 183 Session Progress Content-Type: application/sdp Content-Length: (...) C=IN IP4 0.0.0.0 m=audio 16511 RTP/AVP 97 98 a=visited-realm: Va. operatorV.net IN IP4 192.0.2.4 16511 The SIP 183 Session Progress messa