5.38.2 Connection Release

A Multi-USIM UE may request the network to release the UE from RRC_CONNECTED state in 3GPP access for a USIM due to activity on another USIM in 3GPP access, if both UE and network indicate the Connection Release feature is supported to each other.

In the case of NAS connection release procedure, the UE indicates that it requests to be released from RRC_CONNECTED state, by initiating either a Service Request procedure over 3GPP access or a Registration procedure over 3GPP access (if case the UE needs to perform Registration Update at the same time with this network, including the case where the Registration Request is sent due to mobility outside the Registration Area, i.e. before detecting whether the network supports the feature in the new Tracking Area, provided that the network has already indicated support for Connection Release feature in the current stored Registration Area), by including a Release Request Indication. If supported by the UE and network, the UE may also provide, only together with the Release Request Indication, Paging Restriction Information, as specified in clause 5.38.5, which requests the network to restrict paging. If the UE is performing an Emergency Registration then it shall not include a Release Request Indication.

For NR/5G access, an AS method for the UE to request the network to release the UE from RRC_CONNECTED state is specified in TS 38.300 [27]. This mechanism does not allow the UE to indicate Paging Restrictions.

NOTE 1: When both the access stratum and NAS based approaches for requesting the connection release are supported by the UE and the network, it depends on the UE implementation which of the two to use (for example: based on the preferred end state (RRC_INACTIVE or RRC_IDLE) and whether Paging Restriction Information is to be provided).

NOTE 2: When there is no PLMN-wide support for the Connection Release feature, it can occur that upon Mobility Registration Update with Release Request indication the UE is not released by the network. The UE behaviour, when it detects that the network does not support the feature in a new RA, is outside the scope of this specification.