ed side, is described in Figure 3.12. P-CSCF S-CSCF SIP UPDATE SIP UPDATE SIP UPDATE DIAMETER STR DIAMETER RAR DIAMETER RAA DIAMETER STA SIP 200 OK SIP 200 OK GTPv2-C DELETE BEARER REQUEST SIP 200 OK GTPv2-C DELETE BEARER REQUEST ESM DEACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST S1-AP E-RAB RELEASE COMMAND RRC ConnectionReconfiguration ESM DEACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT RRC ConnectionReconfigurationComplet S1-AP E-RAB RELEASE RESPONSE GTPv2-C DELETE BEARER RESPONSE GTPv2-C DELETE BEARER RESPONSE Figure 3.12. Removing a video stream: received side VoLTE and ViLTE 1), 2), 3) Bob's UA entity (or Alice's) receives the UPDATE request, from the domain homeA. net (or homeB. net), indicating the removal of the video stream. 4) to 7) As described earlier, these messages are used to trigger the release of the dedicated for to the video stream. 8), 9), 10) Bob's UA entity (or Alice's) sends the 200 OK response to the UPDATE request to the domain homeA.net (or homeB. net), indicating the suppression of the video flow. 11) to 16) As described earlier, these messages are used to remove the dedicated bearer for the video stream. 3.9. Emergency call If the mobile detects the emergency call, it performs a particular resource reservation with the EPS network to transmit the INVITE request. The mobile will replace the number dialed by the user by the uniform resource name (URN) which defines the type of emergency call. INVITE urn service: SOS SIP/2.0 The EPS network establishes a bearer (QCI = 5) whose allocation and retention priority (ARP) is higher than that established during the attachment of the mobile. If the mobile does not detect the emergency call, the INVITE request is transmitted on the normal bearer (QCI = 5). If the P-CSCF entity detects the emergency call, it can answer the mobile with an emergency call indication (Figure 3.13). Upon receiving the INVITE message, the P-CSCF entity requests the PCRF entity for the ECGI identifier of the cell where the mobile is located. The P-CSCF entity inserts that