Patent Description:
The following documents are relevant: <CIT> which discusses "MULTI-SIM USER EQUIPMENT AND WIRELESS COMMUNICATION METHOD THEREOF" and <CIT> which discusses"Dual SIM Dual Standby with Caller ID Enhancement".

Some exemplary embodiments outside the scope of the invention are related to a processor of a user equipment (UE) configured to perform operations. The operations include initiating a first voice call with a first network associated with a first subscriber identity module (SIM) of the UE, receiving a paging request from a second network indicating an incoming voice call associated with a second SIM of the UE, wherein the paging request is received while the first voice call is active, performing a radio resource control (RRC) connection setup with the second network and performing one of accepting the incoming voice call or rejecting the incoming voice call.

Other exemplary embodiments outside the scope of the invention are related to a processor of a base station configured to perform operations. The operations include transmitting a paging request to a user equipment (UE) indicating an incoming voice call associated with a second subscriber identity module (SIM) of the UE, wherein the UE receives the paging request while a first voice call associated with a first SIM of the UE is active, performing a radio resource control (RRC) connection setup with the UE, receiving an indication from the UE that the UE should be configured with a single component carrier (CC), suspending dual connectivity (DC) and carrier aggregation (CA) and exchanging session information protocol (SIP) messages with the UE to provide the UE with a caller identification (ID) of the incoming call.

Still further exemplary embodiments outside the scope of the invention are related to a processor of a user equipment (UE) configured to perform operations. The operations include initiating a first voice call with a first network associated with a first subscriber identity module (SIM) of the UE, receiving a paging request from a second network indicating an incoming voice call associated with a second SIM of the UE, wherein the paging request is received while the first voice call is active, performing a radio resource control (RRC) connection setup with the second network, exchanging session information protocol (SIP) messages with the second network to retrieve a caller identification (ID) of the incoming call and tuning a transmitter of the UE to a frequency associated with the second network at one or more predetermined periods during the RRC connection setup and the SIP messages exchange with the second network.

The exemplary embodiments may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The exemplary embodiments describe a user equipment (UE) providing an indication to a base station of a <NUM> new radio (NR) network not to configure the UE with carrier aggregation (CA) and/or multi-radio access network (multi-RAN) dual connectivity (MR-DC). The exemplary embodiments further describe a UE tuning away a transmitter from the frequency of a first network corresponding to a first SIM to the frequency of a second network corresponding to a second SIM during an active call on the first SIM.

The exemplary embodiments are described with regard to a network that includes <NUM> NR radio access technology (RAT). However, the exemplary embodiments may be implemented in other types of networks using the principles described herein.

Throughout this description reference is made to the SIMs performing a function (e.g., communicating with the wireless network). However, those skilled in the art will understand that the SIMs themselves do not perform any functions or operations. Rather, the UE, or more precisely a processor of the UE, implements one or more protocol stacks using the credentials and other information stored on the SIMs and then establishes a connection with networks using the one or more protocol stacks. Thus, when referring to a SIM communicating with a network, this should be understood to include the UE or the processor of the UE communicating via a connection associated with the SIM. Similarly, any other operation attributed to the SIM herein should be understood to be an operation being performed by a protocol stack implemented by the processor using the information provided by the SIM.

The exemplary embodiments are also described with regard to a UE. However, the use of a UE is merely for illustrative purposes. The exemplary embodiments may be utilized with any electronic component that may establish a connection with a network and is configured with the hardware, software, and/or firmware to exchange information and data with the network. Therefore, the UE as described herein is used to represent any electronic component.

When a multi-user subscriber identity module (MUSIM) UE is in a radio resource control (RRC) connected state with a first network via a first SIM (SIM1) and has an ongoing voice call, a paging request for a call (voice/data) may be received from a second network via a second SIM (SIM2). In this scenario, the UE establishes an RRC connection with the second network via the SIM2 to obtain the caller ID associated with incoming call. Typically, all but one (N-<NUM>) of the UE's multiple receivers are allocated to SIM1 for the ongoing voice call and one receiver is allocated to SIM2, which is in an RRC Idle state (or an RRC Inactive state), to receive pages, maintain idle mobility, etc. When SIM2 establishes an RRC connection with the second network to obtain the caller ID of the incoming call, the second network may configure the UE with carrier aggregation (CA) and/or multi-radio access network (multi-RAN) dual connectivity (MR-DC). However, because only one of the UE's receivers is allocated to the SIM2, the RRC configuration of the SIM2 with CA and/or MR-DC will fail, thus failing to provide the caller ID to the UE.

According to some exemplary embodiments, when the MUSIM UE receives a paging request for a voice call on the SIM2 while there is an ongoing call on the SIM1, the UE may provide an indication to the second network that dual connectivity (DC) CA should be suspended such that the second network only configures the UE with a single component carrier (CC) on the SIM2.

Because a MUSIM UE may have multiple receivers and only one transmitter, that transmitter is shared between the SIM1 and the SIM2 when necessary. When there is an active voice call on the SIM1, the UE uses the transmitter primarily for the SIM1 voice call. However, when the SIM2 receives a paging request regarding an incoming call from the second network while the voice call on the SIM1 is still ongoing, the UE uses the transmitter to establish an RRC connection with the second network to obtain the caller ID for the incoming call. However, there is presently no configuration of shared allocation of the transmitter between the SIM1 and SIM2 in such a scenario in the Third Generation Partnership (3GPP) standards.

According to further exemplary embodiments, the UE is configured to tune away the transmitter from a frequency associated with the SIM1 to a frequency associated with the SIM2 during one or more predetermined periods during the caller ID retrieval process in such a way so as not to degrade the SIM1 ongoing call.

<FIG> shows an exemplary network arrangement <NUM> according to various exemplary embodiments. The exemplary network arrangement <NUM> includes a UE <NUM>. It should be noted that any number of UEs may be used in the network arrangement <NUM>. Those skilled in the art will understand that the UE <NUM> may alternatively be any type of electronic component that is configured to communicate via a network, e.g., mobile phones, tablet computers, desktop computers, smartphones, phablets, embedded devices, wearables, Internet of Things (IoT) devices, etc. It should also be understood that an actual network arrangement may include any number of UEs being used by any number of users. Thus, the example of a single UE <NUM> is merely provided for illustrative purposes.

The UE <NUM> may be configured to communicate with one or more networks. In the example of the network configuration <NUM>, the networks with which the UE <NUM> may wirelessly communicate are a <NUM> New Radio (NR) radio access network (<NUM> NR-RAN) <NUM>, an LTE radio access network (LTE-RAN) <NUM> and a wireless local access network (WLAN) <NUM>. However, it should be understood that the UE <NUM> may also communicate with other types of networks and the UE <NUM> may also communicate with networks over a wired connection. Therefore, the UE <NUM> may include a <NUM> NR chipset to communicate with the <NUM> NR-RAN <NUM>, an LTE chipset to communicate with the LTE-RAN <NUM> and an ISM chipset to communicate with the WLAN <NUM>.

The <NUM> NR-RAN <NUM> and the LTE-RAN <NUM> may be portions of cellular networks that may be deployed by cellular providers (e.g., Verizon, AT&T, T-Mobile, etc.). These networks <NUM>, <NUM> may include, for example, cells or base stations (Node Bs, eNodeBs, HeNBs, eNBS, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc.) that are configured to send and receive traffic from UE that are equipped with the appropriate cellular chip set. The WLAN <NUM> may include any type of wireless local area network (WiFi, Hot Spot, IEEE <NUM>. 11x networks, etc.).

The UE <NUM> may connect to the <NUM> NR-RAN <NUM> via the next generation Node B (gNB) 120A and/or the gNB 120B. During operation, the UE <NUM> may be within range of a plurality of gNBs. Thus, either simultaneously or alternatively, the UE <NUM> may connect to the <NUM> NR-RAN <NUM> via the gNBs 120A and 120B. Further, the UE <NUM> may communicate with the eNB 122A of the LTE-RAN <NUM> to transmit and receive control information used for downlink and/or uplink synchronization with respect to the <NUM> NR-RAN <NUM> connection.

Those skilled in the art will understand that any association procedure may be performed for the UE <NUM> to connect to the <NUM> NR-RAN <NUM>. For example, as discussed above, the <NUM> NR-RAN <NUM> may be associated with a particular cellular provider where the UE <NUM> and/or the user thereof has a contract and credential information (e.g., stored on a SIM card). Upon detecting the presence of the <NUM> NR-RAN <NUM>, the UE <NUM> may transmit the corresponding credential information to associate with the <NUM> NR-RAN <NUM>. More specifically, the UE <NUM> may associate with a specific base station (e.g., the gNB 120A of the <NUM> NR-RAN <NUM>).

In addition to the networks <NUM>, <NUM> and <NUM> the network arrangement <NUM> also includes a cellular core network <NUM>, the Internet <NUM>, an IP Multimedia Subsystem (IMS) <NUM>, and a network services backbone <NUM>. The cellular core network <NUM> may be considered to be the interconnected set of components that manages the operation and traffic of the cellular network, e.g. the 5GC for NR. The cellular core network <NUM> also manages the traffic that flows between the cellular network and the Internet <NUM>.

The IMS <NUM> may be generally described as an architecture for delivering multimedia services to the UE <NUM> using the IP protocol. The IMS <NUM> may communicate with the cellular core network <NUM> and the Internet <NUM> to provide the multimedia services to the UE <NUM>. The network services backbone <NUM> is in communication either directly or indirectly with the Internet <NUM> and the cellular core network <NUM>. The network services backbone <NUM> may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionalities of the UE <NUM> in communication with the various networks.

<FIG> shows an exemplary UE <NUM> according to various exemplary embodiments. The UE <NUM> will be described with regard to the network arrangement <NUM> of <FIG>. The UE <NUM> may represent any electronic device and may include a processor <NUM>, a memory arrangement <NUM>, a display device <NUM>, an input/output (I/O) device <NUM>, a transceiver <NUM>, other components <NUM>, and a multi-universal SIM (MUSIM) arrangement <NUM>. The other components <NUM> may include, for example, an audio input device, an audio output device, a battery that provides a limited power supply, a data acquisition device, ports to electrically connect the UE <NUM> to other electronic devices, one or more antenna panels, etc. For example, the UE <NUM> may be coupled to an industrial device via one or more ports. The MUSIM arrangement <NUM> may include a first SIM (SIM1) 240a and a second SIM (SIM2) 240b, each of which may be coupled to different gNBs 120a, 120b (or eNB 122A) of different networks.

The processor <NUM> may be configured to execute a plurality of engines of the UE <NUM>. For example, the engines may include a MUSIM management engine <NUM>. The MUSIM management engine <NUM> may perform various operations related to managing a caller ID retrieval process where it may be indicated to the network <NUM> that a dual connectivity (DC) carrier aggregation (CA) configuration should be suspended and/or tuning the transceiver <NUM> away at predetermined periods of time during the caller ID retrieval process. Examples of this process will be described in greater detail below.

The above referenced engine being an application (e.g., a program) executed by the processor <NUM> is only exemplary. The functionality associated with the engine may also be represented as a separate incorporated component of the UE <NUM> or may be a modular component coupled to the UE <NUM>, e.g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. The engines may also be embodied as one application or separate applications. In addition, in some UE, the functionality described for the processor <NUM> is split among two or more processors such as a baseband processor and an applications processor. The exemplary embodiments may be implemented in any of these or other configurations of a UE.

The memory arrangement <NUM> may be a hardware component configured to store data related to operations performed by the UE <NUM>. The display device <NUM> may be a hardware component configured to show data to a user while the I/O device <NUM> may be a hardware component that enables the user to enter inputs. The display device <NUM> and the I/O device <NUM> may be separate components or integrated together such as a touchscreen. The transceiver <NUM> may be a hardware component configured to establish a connection with the <NUM> NR-RAN <NUM>, the LTE-RAN <NUM>, the WLAN <NUM>, etc. Accordingly, the transceiver <NUM> may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies).

<FIG> shows an exemplary network base station, in this case gNB 120A, according to various exemplary embodiments. The gNB 120A may represent any access node of the <NUM> NR network through which the UEs <NUM> may establish a connection. The gNB 120A illustrated in <FIG> may also represent the gNB 120B.

The gNB 120A may include a processor <NUM>, a memory arrangement <NUM>, an input/output (I/O) device <NUM>, a transceiver <NUM>, and other components <NUM>. The other components <NUM> may include, for example, a power supply, a data acquisition device, ports to electrically connect the gNB 120A to other electronic devices, etc..

The processor <NUM> may be configured to execute a plurality of engines of the gNB 120A. For example, the engines may include an RRC management engine <NUM> for performing operations including configuring an RRC connection for one or more SIMS of the MUSIM arrangement <NUM> of the UE <NUM>. Examples of this process will be described in greater detail below.

The above noted engine being an application (e.g., a program) executed by the processor <NUM> is only exemplary. The functionality associated with the engines may also be represented as a separate incorporated component of the gNB 120A or may be a modular component coupled to the gNB 120A, e.g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. In addition, in some gNBs, the functionality described for the processor <NUM> is split among a plurality of processors (e.g., a baseband processor, an applications processor, etc.). The exemplary aspects may be implemented in any of these or other configurations of a gNB.

The memory <NUM> may be a hardware component configured to store data related to operations performed by the UEs <NUM>, <NUM>. The I/O device <NUM> may be a hardware component or ports that enable a user to interact with the gNB 120A. The transceiver <NUM> may be a hardware component configured to exchange data with the UE <NUM> and any other UE in the system <NUM>. The transceiver <NUM> may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies). Therefore, the transceiver <NUM> may include one or more components (e.g., radios) to enable the data exchange with the various networks and UEs.

<FIG> and <FIG> show signaling diagrams illustrating a method for providing an indication to a network that a MUSIM UE <NUM> should not be configured with carrier aggregation (CA) or multi-radio access network (multi-RAN) dual connectivity (MR-DC) according to various exemplary embodiments. <FIG> illustrates the process when a user rejects an incoming call for the SIM2 240b. At <NUM>, the SIM1 204a is in an RRC connected mode with a first network (a first gNB 120A) for an active voice or data call. It is assumed that the SIM2 240b is in an RRC Idle mode (or RRC Inactive mode). At <NUM>, the UE <NUM> disables early measurement reporting (EMR) on the SIM2 240b, which may have been configured by a second network (a second gNB 120B) prior to SIM2 240b being in the RRC Idle mode (or RRC Inactive mode).

At <NUM>, SIM2 240b receives a paging request from the second network with a paging_cause field that identifies whether this page is for a voice call or a data call. The remaining description of the signaling diagram of <FIG> (as well as the remaining signaling diagrams discussed below) assumes that the paging_cause indicates that the paging request is for a voice call. If, however, the paging cause is for a data call, the UE <NUM> ignores the paging request (and any subsequent retransmissions of the paging request) while the SIM1 240a has an active call with the first network because a data call would require increased use of the single transmitter, which would degrade the call on the SIM1 240a.

At <NUM>, the SIM2 240b transmits an RRC Connection Request to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RRC Connection Setup message to the SIM2 240b. At <NUM>, the SIM2 240b transmits an RRC Connection Setup Complete message to the second gNB 120B. In some embodiments, the RRC complete message may include an request to the second network that a single component carrier (CC) be configured for SIM2. Upon receiving this RRC Connection Setup Complete message, the second gNB 120B suspends dual connectivity (DC) carrier aggregation (CA) at <NUM>.

At <NUM>, the second gNB 120B transmits a Security Mode Command message to the SIM2 240b to configure the UE <NUM> to activate access stratum (AS) security. At <NUM>, the SIM2 transmits a Security Mode Complete message to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RRC Reconfiguration to the SIM2 240b to configure the necessary data radio bearers (DRBs). At <NUM>, the SIM2 240b transmits an RRC Reconfiguration Complete message to the second gNB 120B.

At <NUM>, the second gNB 120B transmits a session initiation protocol (SIP) INVITE message to the SIM2 240b including the caller ID associated with the incoming voice call over the default IMS bearer. As such, the UE <NUM> displays the caller ID and allows the user to decide whether or not to accept the incoming call (and drop the active call on SIM1). As noted above, <FIG> assumes that the user rejects the call. So, at <NUM>, the SIM2 240b transmits a SIP Call Rejection message (e.g., SIP <NUM> message, SIP <NUM> message, etc.) to the second gNB 120B. As a result, the voice call on SIM1 continues and the incoming call on the SIM2 is rejected.

At <NUM>, the SIM2 240b transmits a UE Assistance Information (UAI) message to the second gNB 120B indicating that the RRC connection should be released. In some embodiments, this indication may be a PreferredRRCState field indicating Idle mode (PreferredRRCState=Idle or PreferredRRCState=INACTIVE). In some embodiments, this indication may alternatively include a new cause that indicates to the second gNB 120B that the SIM2 240b is requesting an RRC release. At <NUM>, the second gNB 120B releases the SIM2 RRC connection.

<FIG> illustrates the process when a user accepts an incoming call for SIM2 240b. Since <NUM>-<NUM> are identical to those corresponding steps in <FIG>, an explanation of these operations is omitted here. After the caller ID is displayed to the user, if the user wishes to accept the incoming call on the SIM2, the SIM1 240a transmits, at <NUM>, a SIP BYE message to the first gNB 120A indicating that the voice call on the SIM1 240a should be terminated. At <NUM>, the first gNB 120A transmits an acknowledgement (ACK) for the received SIP BYE message. At <NUM>, the SIM1 240a transmits a UAI message to the first gNB 120A indicating that the RRC connection for the SIM1 240a should be released. In some embodiments, this indication may have a PreferredRRCState field indicating Idle mode (PreferredRRCState=Idle) or Inactive mode (PreferredRRCState=INACTIVE). In some embodiments, this indication may alternatively include a new cause that indicates to the first gNB 120A that the UE is a MUSIM UE and is accepting a call on another SIM.

At <NUM>, the SIM2 240b transmits a SIP Ringing message to the second gNB 120B so that the calling party knows the call is ringing. At <NUM>, the SIM <NUM>240b transmits a SIP <NUM> OK message to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RRC Reconfiguration message to the SIM2 240b indicating the DRBs for voice packets. At <NUM>, the first gNB 120A transmits an RRC Release message to the SIM1 240a to release the SIM1 RRC connection. As such, the SIM1 240a is now in RRC Idle mode (or RRC Inactive mode). At <NUM>, the SIM2 240b transmits an RRC Reconfiguration Complete message to the second gNB 120B indicating that DC-CA may now be resumed (since the user is accepting the SIM2 240b incoming call and all but one of the UE's receivers are now allocated to the SIM2 240b call). At <NUM>, the second gNB 120B resumes DC-CA for the SIM2 240b. At <NUM>, the second gNB 120B transmits an Activate Dedicated evolved packet system (EPS) Bearer Context message to the SIM2 240b to configure the SIM2 240a with the bearer context for the bearer that will be carrying the voice packets.

<FIG> and <FIG> show signaling diagrams illustrating a method for providing an indication to a network that a MUSIM UE <NUM> should not be configured with CA or MR-DC according to various exemplary embodiments. <FIG> illustrates the process when a user rejects an incoming call for the SIM2 240b. At <NUM>, the SIM1 204a is in an RRC connected mode with a first network (a first gNB 120A) for an active voice or data call. It is assumed that the SIM2 240b is in an RRC Idle mode (or RRC Inactive mode). At <NUM>, the UE <NUM> disables EMR on the SIM2 240b, which may have been configured by a second network (a second gNB 120B) prior to the SIM2 240b being in the RRC Idle mode (or RRC Inactive mode).

At <NUM>, the SIM2 240b receives a paging request from the second network with a paging_cause field that identifies whether this page is for a voice call or a data call. The remaining description of the signaling diagram of <FIG> assumes that the paging_cause indicates that the paging request is for a voice call. If, however, the paging cause is for a data call, the UE <NUM> ignores the paging request while the SIM1 240a has an active call with the first network because a data call would require increased use of the UE's single transmitter, which would degrade the call on the SIM1 240a. In addition, from a service perspective, a purely data service (e.g., internet browsing) has a lower priority than a voice service (e.g., VoLTE, VoNR, etc.).

At <NUM>, the SIM2 240b transmits an RRC Connection Request to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RRC Connection Setup message to the SIM2 240b. At <NUM>, the SIM2 240b transmits an RRC Connection Setup Complete message to the second gNB 120B. At <NUM>, the second gNB 120B transmits a Security Mode Command message to the SIM2 240b to configure the UE <NUM> to activate AS security. At <NUM>, the SIM2 240b transmits a Security Mode Complete message to the second gNB 120B.

At <NUM>, the SIM2 240b transmits a UAI message to the second gNB 120B including an indication that DC-CA should be suspended. In some embodiments, this indication may be an implicit indication provided by using a maxAggrBW information element (IE) having a value of zero (maxAggrBW=<NUM>). In some embodiments, the indication may alternatively be an explicit indication in which the SIM2 240b requests a single CC be configured for the SIM2 240b. Upon receiving the UAI message, the second gNB 120B suspends dual connectivity (DC) carrier aggregation (CA) at <NUM>. At <NUM>, the second gNB 120B transmits an RRC Reconfiguration to the SIM2 240b to configure the necessary DRBs. At <NUM>, the SIM2 240b transmits an RRC Reconfiguration Complete message to the second gNB 120B.

At <NUM>, the second gNB 120B transmits a SIP INVITE message to the SIM2 240b including the caller ID associated with the incoming voice call over the default IMS bearer. As such, the UE <NUM> displays the caller ID and allows the user to decide whether or not to accept the incoming call (and drop the active call on SIM1). As noted above, <FIG> assumes that the user rejects the call. So, at <NUM>, the SIM2 240b transmits a SIP Call Rejection message (e.g., SIP <NUM> message, SIP <NUM> message, etc.) to the second gNB 120B. As a result, the voice call on the SIM1 240a resumes and the incoming call on the SIM2 240b is rejected.

At <NUM>, the SIM2 240b transmits a UAI message to the second gNB 120B indicating that the RRC connection should be released. In some embodiments, this indication may be a PreferredRRCState field indicating Idle mode (PreferredRRCState=Idle) or Inactive mode (PreferredRRCState=INACTIVE). In some embodiments, this indication may alternatively include a new cause that indicates to the second gNB 120B that the SIM2 240b is requesting an RRC release. At <NUM>, the second gNB 120B releases the SIM2 RRC connection.

<FIG> illustrates the process when a user accepts an incoming call for SIM2 240b. Since <NUM>-<NUM> are identical to those corresponding steps in <FIG>, an explanation of these operations is omitted here. After the caller ID is displayed to the user, if the user wishes to accept the incoming call on the SIM2 240b, the SIM1 240a transmits, at <NUM>, a SIP BYE message to the first gNB 120A indicating that the voice call on the SIM1 240a should be terminated. At <NUM>, the first gNB 120A transmits an acknowledgement (ACK) for the received the SIP BYE message.

At <NUM>, the SIM2 240b transmits a SIP Ringing message to the second gNB 120B so that the calling party knows the call is ringing. At <NUM>, the SIM <NUM>240b transmits a SIP <NUM> OK message to the second gNB 120B.

At <NUM>, the SIM1 240a transmits a UAI message to the first gNB 120A indicating that the RRC connection for the SIM1 240a should be released. In some embodiments, this indication may be a PreferredRRCState field indicating either Idle mode (PreferredRRCState=Idle) or Inactive mode (PreferredRRCState=Inactive). In some embodiments, this indication may alternatively include a new cause that indicates to the first gNB 120A that the UE is a MUSIM UE and is accepting a call on another SIM.

At <NUM>, the SIM2 240b transmits a UAI message to the second gNB 120B indicating that DC-CA may now be resumed (since the user is accepting the SIM2 240b incoming call and all but one of the UE's receivers are now allocated to the SIM2 240b call). At <NUM>, the first gNB 120A transmits an RRC Release message to the SIM1 240a releasing the SIM1 RRC connection. As such, the SIM1 240a is now in Idle mode or Inactive mode.

At <NUM>, the second gNB 120B resumes DC-CA for the SIM2 240b. At <NUM>, the second gNB 120B transmits an Activate Dedicated EPS Bearer Context message to the SIM2 240b to configure SIM2 with the bearer context for the bearer that will be carrying the voice packets.

<FIG> shows a signaling diagram illustrating a method for tuning away a transmitter <NUM> of a UE <NUM> from a first SIM (SIM1 240a) to a second SIM (SIM2 240b) during a caller ID retrieval procedure on the SIM2 240b according to various exemplary embodiments. It should be noted that in <FIG> the shaded boxes <NUM> (only one of which is labeled) indicate which SIM has control over the transmitter <NUM>. In <FIG>, the transmitter is tuned to the frequency of the second network with which the SIM2 240b communicates during the caller ID retrieval procedure. In some embodiments, the duration of this tune away may be about <NUM> milliseconds (ms).

At 605a and 605b, the internet protocol (IP) multimedia subsystem (IMS) packet data network (PDN) associated with the SIM1 240a and the SIM2 240b are registered (e.g., upon powering on of the UE <NUM>). At <NUM>, a voice call is established on the SIM1 240a with a first network (the first gNB 120A). As such, at <NUM>, the SIM1 240a is in an RRC connected state. Consequently, at <NUM>, the SIM2 240b is in an RRC Idle state (or RRC Inactive state).

At <NUM>, the SIM2 240b receives a paging request from a second network (the second gNB 120B). The paging request includes a paging cause indicating whether the paging request is for a voice call or a data call. In some embodiments, the paging cause may explicitly indicate that the paging request is for a voice call. In such an embodiment, when the UE <NUM> receives this paging cause, if the paging cause does not explicitly indicate that the page is for a voice call, the UE <NUM> may implicitly determine that the page is for a data call. As noted above, it is assumed that the paging request is for a voice call. If, however, the paging request is for a data call, the UE <NUM> may ignore the paging request (and any subsequent retransmissions of the paging request) while the SIM1 240a has an active call with the first network. Because the SIM1 240b has at least one allocated receiver, it can receive the paging request while the voice call is ongoing on the SIM1 240a.

At <NUM>, the UE <NUM> activates a radio frequency (RF) tune away timer upon reception of the paging request (for a voice call). The timer expires at the end of a predetermined time period which is based on what amount of time the transmitter can be tuned away from SIM1 without degrading the active voice call on the SIM1 240a (e.g., <NUM>, <NUM>, <NUM>, etc.). Upon expiration of the RF tune away timer, the transmitter <NUM> is tuned back to the frequency associated with the SIM1 240a regardless of what process is occurring on the SIM2 240b.

At <NUM>, the UE <NUM> tunes away the transmitter <NUM> to a frequency associated with the SIM2 240b. At <NUM>, the SIM2 performs the necessary signaling with the second network (second gNB 120B) to obtain the caller ID of the incoming call in a similar manner as explained above with respect to any of <FIG> (connection establishment and SIP messaging). As illustrated in <FIG>, the SIM2 240b has control of the transmitter <NUM> from the time the transmitter is tuned to the frequency of the second gNB 120B until the end of the caller ID procurement process.

At 645a, either the RF tune away timer expires or the user has rejected the incoming call on the SIM2 240b. In either scenario, the UE <NUM> tunes the transmitter back to the frequency of the first gNB 120A at 645b. Although not illustrated in <FIG>, it should be noted that if the call on the SIM2 240b is accepted, then the transmitter may be tuned back to the frequency of the first gNB 120A only when necessary to drop the voice call on the SIM1 240a. Subsequently, the SIM2 240b will control the transmitter <NUM> for the duration of the SIM2 240b call.

<FIG> show signaling diagrams illustrating a method for a procedure-based tuning away of a transmitter of a UE from a first SIM to a second SIM according to various exemplary embodiments. The method illustrated in <FIG> differ from that of <FIG> in that the tuning away of the transmitter <NUM> in <FIG> is controlled by an RRC layer, a packet transport module (PTM) layer, a packet data convergence protocol (PDCP) layer, an RLC layer, and/or an IMS stack. When a process associated with any of these layers needs to be performed, the transmitter is tuned away to the frequency of the network associated with SIM performing that process. It should be noted that in <FIG> the shaded boxes <NUM> (only one of which is labeled) indicate which SIM has control over the transmitter <NUM>. Each shaded box represents a tuning away of the transmitter <NUM> to the frequency of the corresponding network. In some embodiments, the longest duration that the transmitter <NUM> is tuned away from the first gNB 120A is less than <NUM>.

<FIG> addresses the user rejecting an incoming call on the SIM2 240b. At 702a and 702b, the internet and IMS PDN associated with the SIM1 240a and the SIM2 240b are registered (e.g., upon powering on of the UE <NUM>). At <NUM>, a voice call is established on the SIM1 240a with a first network (the first gNB 120A). As such, at <NUM>, the SIM1 240a is in an RRC connected state. Consequently, at <NUM>, the SIM2 240b is in an RRC Idle state (or RRC Inactive state).

At <NUM>, the SIM2 240b receives a paging request from a second network (the second gNB 120B). The paging request includes a paging cause indicating whether the paging request is for a voice call or a data call. As noted above, it is assumed that the paging request is for a voice call. If, however, the paging request is for a data call, the UE <NUM> may ignore the paging request (and any subsequent retransmissions of the paging request) while the SIM1 240a has an active call with the first network. Because the SIM1 240b has at least one allocated receiver, it can receive the paging request while the voice call is ongoing on the SIM1 240a.

Since the SIM2 240a now needs to establish an RRC connection, the transmitter <NUM> is tuned to the frequency of the second gNB 120B, with which the SIM2 240b communicates (as shown by the shaded box). At <NUM>, the SIM2 240b transmits an RRC Connection Request message to the second network (the second gNB 120B). At <NUM>, the second gNB 120B transmits an RRC Connection Setup message to the SIM2 240b. At <NUM>, the SIM2 240b transmits an RRC Connection Setup Complete message to the second gNB 120B. At <NUM>, the second gNB 120B transmits a radio link control (RLC) acknowledgement (ACK) to the SIM2 240b. In some embodiments, the UE <NUM> is configured to tune the transmitter <NUM> back to the frequency of the first gNB 120A once an RLC ACK is received. If the transmitter <NUM> is tuned away to the SIM1 240a prior to receiving the RLC ACK, then it is possible that the transmitter will need to be tuned back again to the SIM2 240b if an RLC negative ACK (NACK) is received, which means a retransmission would need to be sent. When the transmitter is tuned back to the frequency of the first gNB 120A, the SIM1 <NUM> may transmit/receive any data that was pending while the transmitter <NUM> was tuned to frequency of the SIM2 240b.

At <NUM>, the second gNB 120B transmits a Security Mode Command to configure the UE <NUM> to activate AS security. At <NUM>, the SIM2 240b transmits a Security Mode Complete message to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's RRC layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency (as indicated by the shaded box).

At <NUM>, the second gNB 120B transmits an RRC Reconfiguration message to the SIM2 240b to configure the necessary DRBs. At <NUM>, the SIM2 240b transmits an RRC Reconfiguration Complete message to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's RRC layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

At <NUM>, the second gNB 120B transmits a SIP INVITE message to the SIM2 240b including the caller ID associated with the incoming voice call over the default IMS bearer. As such, the UE <NUM> displays the caller ID and allows the user to decide whether or not to accept the incoming call (and drop the active call on the SIM1 240a). At <NUM>, the SIM2 240b transmits a SIP <NUM> (Session Progress) message to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

As noted above, <FIG> assumes that the user rejects the call. So, at <NUM>, the SIM2 240b transmits a SIP Call Rejection message (e.g., SIP <NUM> message, SIP <NUM> message, etc.) to the second gNB 120B. This rejection may be an indication to the second network that the call on the SIM1 240a is preferred. Since this requires control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. It should be noted that, although not shown, the call establishment process may include other IMS messages (e.g., provisional response ACK (PRACK), PRACK-ACK, Ringing, OK, messages) between the RLC ACK at <NUM> and the call rejection at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

At <NUM>, the second gNB 120B transmits an ACK to the SIM2 240b. At <NUM>, the SIM2 240b transmits an RLC ACK to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's RLC layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. In some embodiments, the SIM2 240b may autonomously release its RRC connection at 746a. If the SIM2 240b is a data preferred SIM, then the SIM2 240b may force an RRC connection release to avoid further exchange of data with the second network, which may unnecessarily cause a tune away of the transmitter <NUM> from the SIM1 240a frequency, thus degrading the active voice call on the SIM1 240a. In some embodiments, the SIM2 240b may alternatively wait for the second network to send the RRC Release message at 746b. If the SIM2 240b is not a data preferred SIM, then it may wait for the network to release the connection.

In some embodiments, to ensure that there is agreement between the SIM2 240b and the second network regarding the RRC connection release of the SIM2 RRC connection, the SIM2 240b may transmit a UAI similar to that discussed above in <NUM> of <FIG> to indicate to the second network that the SIM2 240b is requesting an RRC release (preferredRRCState=IDLE or preferredRRCState=INACTIVE). In response, the second network may send the RRC Release message at 746b to move the SIM2 240b to RRC Idle mode (or RRC Inactive mode).

<FIG> addresses the user ignoring an incoming call on the SIM2 240b. A description of 702a-<NUM> and 746a,b is omitted here for clarity and conciseness. The signaling of <NUM>-<NUM> is also grouped together in <FIG> as "Call Setup. " At <NUM>, the second network (the second gNB 120B) transmits a PRACK message to the SIM2 240b in response to the SIP <NUM> message at <NUM>. At <NUM>, the SIM2 240b transmits a SIP <NUM> OK message to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

At <NUM>, the SIM2 240b transmits a SIP Ringing message to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

As noted above, in <FIG>, it is assumed that the user ignores the incoming call on the SIM2 240b. As such, the call continues to ring until it times out. Once the call times out, the second gNB 120B transmits a SIP Cancel message at <NUM>. At <NUM>, the SIM2 240b transmits a SIP <NUM> OK message to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. At <NUM>, the SIM2 240b transmits a Request Terminated message to the second gNB 120B. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Since the transmissions at <NUM> and <NUM> require control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

At <NUM>, the second gNB <NUM> transmits an ACK message to the SIM2 240b. At <NUM>, the SIM2 240b transmits an RLC ACK to the second gNB 120B. Since this requires control of the transmitter <NUM>, the UE's RLC layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. As discussed above, the SIM2 240b may autonomously release its RRC connection at 746a, wait for the second network to send the RRC Release message at 746b, or transmit a UAI to the second network to request an RRC release.

<FIG> addresses the user accepting an incoming call on the SIM2 240b. A description of 702a-<NUM> is omitted here for clarity and conciseness. The signaling of <NUM>-<NUM> is again grouped together in <FIG> as "Call Setup. " At <NUM>, the SIM2 240b transmits a SIP <NUM> OK message to the second network (the second gNB 120B) to indicate that the call is being accepted. Since this transmission requires control of the transmitter <NUM>, the UE's IMS layer may tune the transmitter to the SIM2 240b frequency prior to the transmission at <NUM>. At <NUM>, the second gNB 120B transmits an RLC ACK to the SIM2 240b. Once this RLC ACK is received, the transmitter is tuned back to the SIM1 240a frequency.

Now that the SIM1 240a has control of the transmitter and the user has decided to accept the incoming call on the SIM2 240b, the SIM1 240a transmits a SIP BYE message to the first network (the first gNB 120A) at <NUM>. The first gNB 120A transmits a SIP <NUM> OK message to the SIM1 240a. The SIM1 240a transmits an RLC ACK to the first gNB 120A. Once this RLC ACK is transmitted, the transmitter <NUM> may be tuned back to the SIM2 240b frequency so that the call on the SIM2 may proceed. While the SIM1 is terminating the voice call on the SIM1, the second gNB 120B transmits an ACK message to the SIM2 240b at <NUM>.

Similar to the behavior of the SIM2 240b in releasing the RRC connection, the SIM1 240a may autonomously release its RRC connection at 746a or wait for the second network to send the RRC Release message at 746b depending on whether or not SIM1 240a is a data preferred SIM. As a result, the SIM1 240a is in an RRC Idle mode (or RRC Inactive mode) at <NUM>.

In some embodiments, to ensure that there is agreement between the SIM1 240a and the first network regarding the RRC connection release of the SIM1 RRC connection, the SIM1 240a may transmit a UAI similar to that discussed above in <NUM> of <FIG> to indicate to the first network that the SIM1 240a is requesting an RRC release (preferredRRCState=IDLE or preferredRRCState=INACTIVE). In response, the first network may send the RRC Release message at 786b to move the SIM1 240a to RRC Idle mode(or RRC Inactive mode) at <NUM>.

At <NUM>, the SIM2 240b transmits an RLC ACK to the second gNB 120B in response to the ACK received from the second gNB 120B at <NUM>. At <NUM>, the voice call on the SIM2 240b is established. As such, the SIM2 240a is now in RRC connected mode at <NUM>.

<FIG> shows a signaling diagram illustrating a method for a transmission-based tuning away of a transmitter of a UE from a first SIM to a second SIM according to various exemplary embodiments. The method illustrated in <FIG> differs from that of <FIG> and <FIG> in that the tuning away of the transmitter <NUM> in <FIG> is controlled by the medium access control (MAC) layer or L1 layer. When there is an uplink buffer at the MAC layer, the MAC layer will reserve the transmitter <NUM> for the SIM that needs to perform the transmission of the protocol date unit (PDU). It should be noted that in <FIG> the shaded boxes <NUM> (only one of which is labeled) indicate which SIM has control over the transmitter <NUM>. Each shaded box represents a tuning away of the transmitter <NUM> to the frequency of the corresponding network (gNB).

<FIG> addresses the user rejecting an incoming call on the SIM2 240b. A description of the signaling in 802a-846b is omitted here since this signaling is identical to that of 702a-746b in <FIG>. The difference between method illustrated in <FIG> and that of <FIG> is the tuning away of the transmitter <NUM>. As explained above, in <FIG>, the tuning away is process based. However, in <FIG>, the tuning away is transmission based. As such, the transmitter <NUM> is tuned to the frequency of the second gNB 120B whenever the SIM2 240b needs to send a transmission to the second network (the gNB 120B). As a result, the active voice call on the SIM1 240a is interrupted more frequently but for significantly shorter time durations (e.g., less than <NUM> for each occurrence). A discussion of this transmission-based tuning away of the transmitter <NUM> for the scenarios in which the incoming SIM2 240b call is ignored or accepted is omitted here for brevity. It should be noted however that the same transmission-based tuning away principle applies to those scenarios.

<FIG> shows an exemplary MUSIM UE <NUM> having a single transmitter <NUM>, as described in the above embodiments. As illustrated in <FIG>, in some embodiments, the UE <NUM> may include a first SIM (SIM1 901a) having an associated protocol stack (protocol stack <NUM>902a) and an associated receiver (Rx1 904a). Similarly, the UE <NUM> may include a second SIM (SIM1 901b) having an associated protocol stack (protocol stack <NUM>902b) and an associated receiver (Rx2 904b). Both the SIM1 901a and the SIM2 901b share a single transmitter <NUM> in the manner explained above. The SIM1 901a communicates with the first base station (Base Station <NUM>908a) of a first network (Network <NUM>910a) via the Rx1 904a and the Tx <NUM>. The SIM2 901b communicates with a second base station (Base Station <NUM>908b) of a second network (Network <NUM>910b) via the Rx2 904b and the Tx <NUM>. Although only two receivers (RX1 904a, RX2 904b) are shown in <FIG>, it should be noted that the UE <NUM> may include multiple receivers.

<FIG> shows an exemplary MUSIM UE <NUM> having multiple transmitters according to various exemplary embodiments. <FIG> shows an exemplary transmission power graph relating to power management of the multi-transmitter MUSIM UE of <FIG>. As illustrated in <FIG>, in some embodiments, the UE <NUM> may include a first SIM (SIM1 901a) having an associated protocol stack (protocol stack <NUM>902a), an associated receiver (Rx1 904a), and an associated transmitter (Tx1 906a). The SIM1 901a communicates with first base station (Base Station <NUM>908a) of a first network (Network <NUM>908a) via a Rx1 904a and a Tx1 906a. Similarly, the UE <NUM> may include a second SIM (SIM1 901b) having an associated protocol stack (protocol stack <NUM>902b), an associated receiver (Rx2 904b), and an associated transmitter (Tx2 906b). The SIM2 901b communicates with a second base station (Base Station <NUM>908b) of a second network (Network <NUM>908b) via a Rx2 904b and a Tx2 906b. Although only two receivers (RX1 904a, RX2 904b) are shown in <FIG>, it should be noted that the UE <NUM> may include multiple receivers.

In the following description of <FIG>, it is assumed that the SIM1 901a is in an RRC connected mode and has an active voice call with the Tx1 906a tuned to the frequency of base station <NUM>908a. When a caller ID retrieval process (as explained above) begins (upon reception of paging request indicating a voice call), the Tx2 906b is tuned to the frequency of the base station <NUM>908a. In some embodiments, when the SIM2 901b needs to transmit messages to the base station <NUM>908b for the caller ID retrieval process, the max Tx1 power is reduced to <NUM>, as indicated by 912a, and the max Tx2 power is set to some nonzero value, as indicated by 912b. Conversely, when the SIM2 901b has completed these transmissions, the max Tx2 power is reduced to <NUM>, as indicated by 914b, and the max Tx1 power is set to some nonzero value, as indicated by 914a. This duty cycle may be controlled by the protocol stacks 902a,b based on a priority of the transmissions on the two SIMs 901a,b.

In a first example, a method performed by a user equipment (UE), comprising initiating a first voice call with a first network associated with a first subscriber identity module (SIM) of the UE, receiving a paging request from a second network indicating an incoming voice call associated with a second SIM of the UE, wherein the paging request is received while the first voice call is active, performing a radio resource control (RRC) connection setup with the second network and performing one of accepting the incoming voice call or rejecting the incoming voice call.

In a second example, the method of the first example, wherein, when the incoming voice call is rejected, the method further comprising transmitting a UE assistance info (UAI) message to the second network including an RRC connection release request and receiving an RRC connection release from the second network.

In a third example, the method of the first example, wherein, when the incoming voice call is accepted, the method further comprising terminating the first voice call, transmitting a UE assistance info (UAI) message to the first network including an RRC connection release request and receiving an RRC connection release from the first network.

In a fourth example, the method of the first example, further comprising transmitting an indication to the second network that the UE should be configured with a single component carrier (CC) and exchanging session information protocol (SIP) messages with the second network to retrieve a caller identification (ID) of the incoming call.

In a fifth example, the method of the fourth example, wherein the indication is configured to cause the network to suspend dual connectivity (DC) and carrier aggregation (CA).

In a sixth example, the method of the fourth example, wherein the indication is an explicit indication provided as part of an RRC Connection Setup Complete message sent by the UE to the second network.

In a seventh example, the method of the fourth example, wherein the indication is an implicit indication provided as part of a UE assistance information (UAI) message sent by the UE to the second network, wherein the implicit indication is a maxAggrBW information element (IE) having a value of zero.

In an eighth example, the method of the seventh example, further comprising transmitting a second indication to the second network that dual connectivity (DC) and carrier aggregation (CA) may resume.

In a ninth example, the method of the eighth example, wherein the second indication is provided as part of an RRC Reconfiguration Complete message sent by the UE to the second network.

In a tenth example, the method of the eighth example, wherein the second indication is provided as part of UE assistance info (UAI) message sent by the UE to the second network.

In an eleventh example, a user equipment (UE) comprises a transceiver configured to communicate with a first network and a second network and a processor communicatively coupled to the transceiver and configured to perform any of the operations of the first through tenth examples.

In an twelfth example, a method performed by a base station, comprising transmitting a paging request to a user equipment (UE) indicating an incoming voice call associated with a second subscriber identity module (SIM) of the UE, wherein the UE receives the paging request while a first voice call associated with a first SIM of the UE is active, performing a radio resource control (RRC) connection setup with the UE, receiving an indication from the UE that the UE should be configured with a single component carrier (CC); suspending dual connectivity (DC) and carrier aggregation (CA) and exchanging session information protocol (SIP) messages with the UE to provide the UE with a caller identification (ID) of the incoming call.

In a thirteenth example, the method of the twelfth example, wherein the indication is an explicit indication provided as part of an RRC Connection Setup Complete message received from the UE.

In a fourteenth example, the method of the twelfth example, wherein the indication is an implicit indication provided as part of a UE assistance information (UAI) message received from the UE.

In a fifteenth example, the method of the fourteenth example, wherein the implicit indication is a maxAggrBW information element (IE) having a value of zero.

In a sixteenth example, the method of the twelfth example, wherein, when the incoming voice call is rejected, the method further comprises receiving a UE assistance info (UAI) message from the UE including an RRC connection release request and transmitting an RRC connection release to the UE.

In a seventeenth example, the method of the twelfth example, wherein, when the incoming voice call is accepted, the method further comprises receiving a second indication from the UE that DC-CA may resume and resuming DC-CA.

In an eighteenth example, the method of the seventeenth example, wherein the second indication is provided as part of an RRC Reconfiguration Complete message received from the UE.

In a nineteenth example, the method of the seventeenth example, wherein the second indication is provided as part of UE assistance info (UAI) message received from the UE.

In an twentieth example, a base station comprises a transceiver configured to communicate with a user equipment (UE) and a processor communicatively coupled to the transceiver and configured to perform any of the operations of the twelfth through nineteenth examples.

In a twenty first example, a method performed by a user equipment (UE), comprising initiating a first voice call with a first network associated with a first subscriber identity module (SIM) of the UE, receiving a paging request from a second network indicating an incoming voice call associated with a second SIM of the UE, wherein the paging request is received while the first voice call is active, performing a radio resource control (RRC) connection setup with the second network, exchanging session information protocol (SIP) messages with the second network to retrieve a caller identification (ID) of the incoming call and tuning a transmitter of the UE to a frequency associated with the second network at one or more predetermined periods during the RRC connection setup and the SIP messages exchange with the second network.

In a twenty second example, the method of the twenty first examples, wherein, when the incoming voice call is rejected and the second SIM is a data-preferred SIM, the method further comprises performing an RRC connection release for the RRC connection with the second network, wherein performing the RRC connection release comprises transmitting a UE assistance info (UAI) message to the second network including an RRC connection release request and receiving an RRC connection release from the second network.

In an twenty third example, a user equipment (UE) comprises a transceiver configured to communicate with a first network and a second network and a processor communicatively coupled to the transceiver and configured to perform any of the operations of the twenty first and twenty second examples.

Those skilled in the art will understand that the above-described exemplary embodiments may be implemented in any suitable software or hardware configuration or combination thereof. An exemplary hardware platform for implementing the exemplary embodiments may include, for example, an Intel x86 based platform with compatible operating system, a Windows OS, a Mac platform and MAC OS, a mobile device having an operating system such as iOS, Android, etc. In a further example, the exemplary embodiments of the above described method may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor.

Although this application described various aspects each having different features in various combinations, those skilled in the art will understand that any of the features of one aspect may be combined with the features of the other aspects in any manner or which is not functionally or logically inconsistent with the operation of the device or the stated functions of the disclosed aspects.

Claim 1:
A processor of a multi-user subscriber identity module, MUSIM, user equipment, UE (<NUM>), configured to perform operations comprising:
initiating a first voice call with a first network associated with a first subscriber identity module, SIM, of the MUSIM UE (<NUM>);
receiving a paging request from a second network indicating an incoming voice call associated with a second SIM of the MUSIM UE (<NUM>),
UD, wherein the paging request is received while the first voice call is active;
performing a radio resource control, RRC, connection setup with the second network;
performing one of accepting the incoming voice call or rejecting the incoming voice call;
characterised in that
when the incoming voice call is rejected:
transmitting a UE assistance information, UAI, message to the second network including an RRC connection release request; and
receiving an RRC connection release from the second network; and
when the incoming voice call is accepted:
terminating the first voice call;
transmitting the UAI message to the first network including an RRC connection release request; and
receiving the RRC connection release from the first network.