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The present document examines several use cases in support of UE with multiple USIMs (MUSIM UE) provided by same or different MNOs and identifies new potential service requirements for emergency services and normal services among USIMs.
With the growing demand in the consumer market, many commercially deployed devices support more than one USIM (typically two) in which the USIMs may be from the same or from different MNOs. The 3GPP system performance and user experiences are greatly impacted in the following two facts:
Currently, support for multi-USIM is handled in an implementation-specific manner without any support from 3GPP specifications, resulting in a variety of implementations and UE behaviours.
A multi-USIM device implementation typically uses common radio and baseband components that are shared among the multiple USIMs. For example, while actively communicating with the first system associated with USIM A, the UE needs to occasionally check the other system associated with USIM B, e.g. to monitor the paging channel, perform signal measurements, or read the system information, and determine if it needs to respond to a paging request from the other system.
The aim of this study is to study aspects indicated in objectives agreed in FS_MUSIM SID in the following use cases and provide corresponding service requirements for enabling multi-USIM devices supports in 3GPP system:
Enabling the support for terminal with multiple USIMs
Supporting Mobile-Terminated Service
Handling of emergency calls and sessions
The modes of operation for the MUSIM UE is indicated in GSMA Requirements for Multi SIM Devices Version 5.0.
full Table of Contents for TR 22.834 Word version: 17.1.0