ge. 45) The PCRF entity responds to the P-CSCF entity with the DIAMETER AAA message. 46), 47), 48) The P-CSCF entity forwards the 200 OK response to the INVITE request to the domain homeA.net. 49), 50), 51) The ACK request of the 200 OK response is received from the domain homeA. net. 3.6. Termination of VoLTE session The termination of the session can be triggered by UA, P-CSCF or IMS- GWF entity, using the BYE method. Termination of the session can be initiated by either (Alice's or Bob's) UA entity when the communication has finished. The P-CSCF entity can also end the session if the mobile is no longer within radio coverage. The PCRF entity sends this information to the P-CSCF entity by way of a DIAMETER ASR (Abort-Session-Request) message. The IMS-GWF entity is an application server which controls the session in the case of pre-paid use. When the user's credit is exhausted, the IMS-GWF entity ends the session. Two BYE requests are needed to terminate the session: one request sent to Alice's UA entity and the second to Bob's UA entity. Basic Procedures 3.6.1. Initiated side The procedure for clearing the VoLTE session initiated by the UA entity, at the initiated side, is described in Figure 3.7. P-CSCF S-CSCF SIP BYE SIP BYE SIP BYE DIAMETER STR DIAMETER RAR DIAMETER RAA DIAMETER STA SIP 200 OK SIP 200 OK SIP 200 OK GTPv2-C DELETE BEARER REQUEST 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 ConnectionReconfiguration Complete S1-AP E-RAB RELEASE RESPONSE GTPv2-C DELETE BEARER RESPONSE GTPv2-C DELETE BEARER RESPONSE Figure 3.7. Termination of VoL TE session: initiated side 1), 2), 3) The release of the session is initiated by Alice's UA entity (or Bob's), which forwards the BYE request to the domain homeB. net homeA. net). 4) On receipt of the BYE request, the P-CSCF entity informs the PCRF entity for the release of the session in the DIAMETER STR (Session- Termina