6.4 Operator Policy and User Preferences

23.2373GPPIP Multimedia Subsystem (IMS) Service ContinuityRelease 17Stage 2TS

Operator Policy is provisioned in the network by the operator, and should be communicated to the UE during initial provisioning or via OMA Device Management [7]. Operator policy should be communicated to the UE, via OMA Device Management, whenever the policy is updated by the operator.

Operator policy shall indicate, for each supported type of media or group of media:

– a list of access networks that are restricted for originating sessions and Access Transfer;

– a list of preferred access networks (in order of priority) to be used by the UE with SC capabilities for originating sessions and Access Transfer, when those access networks become available and Access Transfer is possible;

– whether the UE with SC capabilities "shall"/"should"/"may" start transferring media flow(s) to target access networks with higher priorities than the current access network, when the target access networks become available and Access Transfer is possible;

– by indicating "shall" the operator mandates the UE to start Access Transfer according to the home operator’s list of preferred access networks as soon as possible;

– by indicating "should" the operator recommends the UE to start Access Transfer according to the home operator’s list of preferred access networks, if Access Transfer is possible and desirable after having taken into account the Local Operating Environment Information;

– by indicating "may" the operator leaves the UE free to decide whether or not to start Access Transfer in accordance with user preferences (when configured), if Access Transfer is possible and desirable after having taken into account the Local Operating Environment Information. Whenever user preferences are not configured, the UE shall to take into account the home operator’s list of preferred access networks;

– whether to keep or drop non transferable media flow(s) in the case of partial Access Transfer.

NOTE 1: Operator policy for Access Transfer needs to be consistent with operator policy for T-ADS.

User preferences may indicate for example:

– preferred access/domain, i.e. CS preferred or IMS preferred, and which IP-CAN within IMS.

The Local Operating Environment Information is implementation specific and may comprise of such items as, radio environment information, quality of IP connection (jitter, delay and packet loss), application specific requirements, memory considerations, power considerations, etc.

The UE shall take in account operator policy, user preferences and the Local Operating Environment Information when deciding which access to use for outgoing sessions, performing UE assisted T-ADS, or before considering initiating Access Transfer.

NOTE 2: If the "IMS voice over PS Session Supported Indication" indicator, see TS 23.060 [27] and TS 23.401 [28], is not set for a specific 3GPP IP‑CAN and if there is no ongoing IMS voice over PS session, this IP‑CAN cannot be used for voice, even if set to preferred by the user preferences.