5.38.1 General

A network and a Multi-USIM UE may support one or more of the following features for Multi-USIM UE operation:

• Connection Release as described in clause 5.38.2;
• Paging Cause Indication for Voice Service, as described in clause 5.38.3;
• Reject Paging Request, as described in clause 5.38.4;
• Paging Restriction, as described in clause 5.38.5;
• Paging Timing Collision Control, as described in clause 5.38.6.

In the Registration procedure (as specified in clause 4.2.2.2.2), when a Multi-USIM UE has more than one USIM active, supports and intends to use one or more Multi-USIM specific features, it indicates to the AMF the corresponding Multi-USIM feature(s) are supported (except for the Paging Timing Collision Control feature). Based on the received indication of the supported Multi-USIM features from the UE, the AMF shall indicate to the UE the support of the Multi-USIM features based on the Multi-USIM features supported by network and any preference policy by the network, if available. When a UE returns to having only one USIM active from a Multi-USIM UE that previously indicated to the network it supported Multi-USIM feature(s), the UE shall indicate all the Multi-USIM features are not supported to the network for that USIM. The AMF shall only indicate the support of Paging Restriction feature together with the support of either Connection Release feature or Reject Paging Request feature.

The Multi-USIM UE includes the support of individual features for Connection Release, Paging Cause Indication for Voice Service, Reject Paging Request and Paging Restriction as specified in clause 5.4.4a.

NOTE: The Paging Timing Collision Control feature being based on the Mobility Registration Update and it doesn't require capability exchange between the UE and network.

The network shall not indicate support for any Multi-USIM feature to the UE as part of the Emergency Registration procedure.

A Multi-USIM UE shall use a separate PEI for each USIM when it registers with the network.