When a device supports multiple USIMs provided by the same or different PLMNs, it is important for the 3GPP system to specify how it can support these terminals with multiple USIMs that are registered at the same time in terms of service priorities and terminal capabilities.

This is the use case about Peter Parker and Mary Jane, Part I. Mary Jane moved to London and Peter follows her to give her a surprise. Peter's mobile phone supports multiple UICCs. After he landed at Heathrow airport, he bought a travel SIM card from vending machine.

Step 1: Step 2: Step 3:

Peter is able to start using his travel USIM for local phone call and data connection services in London and receive the phone call and SMS from his first USIM simultaneously.

According to clause 13.3 of TS 22.101, the following use case is currently supported in EPS/5GS.

• A single terminal may support the use of multiple UICCs and only one UICC shall be active (registered) at a time to access a PLMN.
• Each UICC can contain one or more than one USIMs.

However, according to the current requirements in TS 22.101, it is not yet possible to have multiple active (registered) USIMs.

[PR.5.1.6-1]: [PR.5.1.6-2]: [PR.5.1.6-3]: [PR.5.1.6-4]:

Currently, support for devices with multi-USIM is handled in an implementation-specific manner resulting in a variety of implementations and UE behaviours. When using common radio and baseband components that are shared among the multiple USIMs, the UE needs to occasionally check the other system associated with USIM B while actively communicating with the first system associated with USIM A, e.g. to monitor the paging channel, perform signal measurements, or read the system information. In order to preserve the quality of established communications while avoiding the potential loss of calls, it would be beneficial if the network were able to assist the UE in deciding e.g. whether or not to respond to a paging request from the other system associated to another active USIM. The exact UE behaviour could also be further assisted by configuring service prioritization policies in the UE.

This is the use case about Peter Parker and Mary Jane, part II. Peter's mobile phone supports multiple USIMs and he has started using his travel USIM card for local phone call and data connection services in London, and his first USIM to receive phone calls and SMS simultaneously. Peter, using Non-IMS voice service associated to travel USIM, calls Mary to let her know he has arrived in London. At the same time in New York, NYPD is dealing with an international crime and the suspects are escaping to London. NYPD decides to phone Peter for help.

Step 1: Step 2:

For case 1 and case 2B, Peter is happy to have a date with Mary when talking to Mary without being interrupted by the voice call from the first USIM. For case 2A, Peter picks up the phone call from NYPD and prepares to catch the criminals in London. Mary is back on the call when the network resumes the call based on the UE request. Peter manages to defeat the criminals in London and have a date out with Mary.

N/A

[PR.5.2.2-1]:

• IMS and non-IMS based Voice service.
• IMS and non-IMS based SMS or USSD
• IMS service other than voice or SMS
• Other service not listed above e.g. data services including video.

[PR.5.2.2-2]: [PR.5.2.2-3]: [PR.5.2.2-4]: [PR.5.2.2-5]: [PR.5.2.2-6]:

With the support of multi-USIM devices, it is important for the 3GPP system to specify service requirements to ensure emergency services provisioning and avoid conflicting behaviour among multiple USIMs for originating emergency call and terminating emergency call-back.

This is the use case about Peter Parker and Mary Jane, part III. When Peter is on the way to meet Mary, Mary is kidnapped by the criminals to an abandoned factory and calls for help from Peter. Peter makes his way to the factory and tries to rescue Mary. When Peter is fighting with criminals, Mary grabs Peter's phone, which has a first USIM and travel USIM installed, and dials IMS emergency voice call to London police.

Case 1: one of the USIM is normal service Case 2: both of the USIM are in normal service Case 3: both of the USIM are in normal service, but the travel SIM is data only

Peter successfully beats up the criminals and saves Mary's life. They are happily reunited. London police officers arrive right on time to catch the criminals.

N/A

[PR.5.3.6-1]:

• USIM in normal service
• USIM in limited service state

[PR.5.3.6-2]:

Many commercially deployed devices support more than one USIM (typically two). For cost efficiency reasons, a multi-USIM device implementation typically uses common radio and baseband components that are shared among the multiple USIMs. This use case enables that a user using a device with two USIMs with such implementation can have an incoming call associated with one USIM while having a call associated with another USIM. The two USIMs may be from the same or from different MNOs.

User A has a mobile phone with two USIMs, i.e. USIM 1 and USIM 2. The two USIMs may be from the same or from different MNOs. The mobile phone uses common radio and baseband components that are shared between the two USIMs.

1. User A has a call associated with USIM 1.
2. During the call, user B calls USIM 2 of user A.
3. The mobile phone of user A rings and informs user A that there is an incoming call associated with USIM 2.
4. User A hangs up the call from user B for USIM 2 and continue the first call for USIM 1.
5. Or User A decides to answer the call from user B, User A answers this call and hangs up the first call for USIM 1.
6. When the call from user B ends, user A resume the first call for USIM 1.

None.

None.

[PR.5.4.6-1]:

Many commercially deployed devices support more than one USIM (typically two). For cost efficiency reasons, a multi-USIM device implementation typically uses common radio and baseband components that are shared among the multiple USIMs. This use case enables that a user using a device with two USIMs with such implementation can have voice service associated with one USIM and data service associated with the other USIM simultaneously. The two USIMs may be from the same or from different MNOs.

User A has a mobile phone with two USIMs, i.e. USIM 1 and USIM 2. The two USIMs may be from the same or from different MNOs. The mobile phone uses common radio and baseband components that are shared between the two USIMs.

1. User A is using the multi-USIM smartphone to play the game via the data connection associated with USIM 1.
2. User B calls USIM 2 of user A.
3. The mobile phone of user A rings and informs user A that there is an incoming call associated with USIM 2.
4. User A answers the call from user B and keeps playing the game. And the call will not impact the gaming experience, i.e., will not cause lag or packet loss.

After the call from user B ends, user A can keep playing the mobile game.

None.

[PR.5.5.6-1]: [PR.5.5.6-2]:

Without any additional support MUSIM UEs in DSDS mode may operate in such a way as to reduce User experience due to interruptions in service when paging collision occurs. This use case seeks to avoid this degradation of service experienced by the user as well as, if possible, wasted resources in the system. Examples of waste in the system are: additional signalling (of any kind) between the UE and the network, unnecessary paging, unnecessary interruptions of service on the UE to respond to paging.

J has a MUSIM UE in DSDS mode. J uses services associated with one USIM.

J has a MUSIM UE in DSDS mode. J uses data download services (e.g. streaming music) associated with one USIM. J receives a mobile terminated call associated with another USIM, and speaks to the caller.

J's user experience is excellent. The use of MUSIM in DSDS mode has resulted in a minimum of wasted signalling and resources.

N/A

[PR.5.6.2-1]: [PR.5.6.2-2]:

Dual SIM mobile phones, one form of multi-USIM devices, have become mainstream since late 2000s in many countries, which refer to mobile phones that support use of multiple UICCs [GSMA TS.37]. So far switching between multiple USIMs / UICCs is achieved by terminal side implementations while remaining transparent to mobile networks. With the current implementations, a Dual SIM phone either allows users to switch between two separate mobile network services manually, has hardware support for keeping both connections in a "standby" state for automatic switching, or has individual transceivers for maintaining both network connections at once. Enabling 3GPP system support of multi-USIM devices has benefits, while it also introduces some potential security risks. Separating personal and business uses Dual SIM Phone is one of the options that allow the user to have both a personal and business phone number within the same phone. Users can place their 'work' USIM or a UICC in the phone alongside a personal USIM or a UICC, so that they only have to carry one handset. Many business phones would enable the remote control / management from the (owner) company. Security guarantee for both personal use and business use is essential. Data privacy is crucial in many regions based on regulatory requirements. Therefore, it is very important that personal usage to be separated / isolated from business usage. In addition, separation of the associated subscriptions/preferences with different UICCs/USIMs is also necessary. Efficiency Dual SIM phones make it easier for tariff hopping. For example, a user may want a separate UICC/USIM for data services only, and Dual SIM phones would allow the user to carry both subscriptions in one single phone without repeated UICC replacement. This keeps the primary number contactable with the addition of data only UICC/USIM for use on the go. In this use case these two UICCs/USIMs have subscriptions for different services, for example the primary UICC/USIM for phone calls while the additional UICC/USIM for data services. In addition to security and data privacy guarantee for each UICC/USIM, clear separation between the associated subscriptions/preferences becomes more important.

The following definitions captured in TR 21.905 are applicable. UICC: Universal Subscriber Identity Module (USIM): Concerning the related service principles specified in TS 22.101, some are still applicable while some may require careful review, for example In clause 13.3 of TS 22.101 "Terminals and Multiple UICCs" -- A single terminal may support the use of multiple UICC (e.g. with applications like USIM and/or banking, credit card, ...). Only one UICC shall be active at a time to access a PLMN. In clause 13.1.4 of TS 22.101 "Multiple USIMs per UICC" -- The standard shall support more than one USIM per UICC even when those USIMs are associated with different home environments. Only one of the USIMs or the SIM shall be active at a given time. While the UE is in idle mode, it shall be possible for the user to select/reselect one USIM application amongst those available on the UICC. At switch on, the Last Active USIM shall be automatically selected. The Last Active USIM shall be stored on the UICC. By default if there is no Last Active USIM defined in the UICC, the user shall be able to select the active USIM amongst those available on the UICC. The standard must not prevent the coexistence of USIM applications, each associated with different home environments on the same UICC, so long as the security problems which arise from such a coexistence are solved.

[PR.5.7.3-1] [PR.5.7.3-2] [PR.5.7.3-3]