Section: 4.3.18.2.1 Originating IMS-based MPS Session
Content: IMS based MPS sessions are permitted to be originated from any UE, in addition to MPS-subscribed UEs. The MPS-subscribed UE, based on the MPS IMS subscription information, operator's policy and national/regional regulations, may be given priority treatment for the default bearer and the EPS bearer carrying IMS signalling in the EPS prior to and during IMS-based MPS invocation. Further, priority treatment in the EPS for signalling and media bearers may be modified/established via dynamic PCC based on the session authorization information received from the AF. As the IMS media bearer is established after the IMS session of the MPS service has been established, it can be assigned with correct ARP value when it is established. However IMS signalling related EPS bearer needs to be upgraded if it has not been assigned with an appropriate ARP setting for the MPS service when the IMS session of the MPS service has been initiated. Also to avoid cases where the default bearer may not be allocated resources in the handover case, due to low ARP priority for the PDN connection, it is necessary to assure that the default bearer has an ARP setting appropriate for the MPS service.