DESC:FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

METHOD TO HANDLE INCOMING CS CALL WHILE VOLTE CALL ACTIVE IN DSDS CASE

SAMSUNG R&D INSTITUTE INDIA – BANGALORE PRIVATE LIMITED,
#2870, Orion Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanekundi Circle,
Marathahalli Post, Bangalore – 560037,
Karnataka, India,
an Indian Company

The following Specification particularly describes the invention and the manner in which it is to be performed

RELATED APPLICATION

The present invention claims benefit of the Indian Provisional Application No. 2089/CHE/2015 titled "METHOD TO HANDLE INCOMING CS CALL WHILE VOLTE CALL ACTIVE IN DSDS CASE” by Samsung R&D Institute India – Bangalore Private Limited, filed on 23rd April 2015, which is herein incorporated in its entirety by reference for all purposes.

FIELD OF THE INVENTION

The present invention generally relates to wireless communication and particularly relates to a method for handling incoming circuit switched (CS) call while call is active in a Dual SIM device.

BACKGROUND OF THE INVENTION

Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP).

Dual/ Multi SIM user equipment’s (UE) are highly popular among cell phone users these days. Their ability to allow communication through two different networks/numbers is highly functional. Especially for employees/sales people, who maintain two or more different numbers for family and professional contacts, these dual/ multi SIM devices are greatly useful. Further, they also come in handy in case of emergencies, when any one of the SIMs is non-functional due to no signals or is out of account balance.

Dual/multi SIM devices are basically classified into three categories, based on the functionality and access of network for the SIMs: dual SIM shift (DSS) phone, dual SIM dual active (DSDA) phone, and dual SIM dual standby (DSDS) device.

Consider a scenario, where a DSDS Dual SIM phone supports LTE+GSM/WCDM / LTE+GSM / LTE+UMTS. An active packet switch (PS) voice call (ex: VoLTE or VOIP) is ongoing on SIM1, and a new incoming circuit switch (CS) call (2G/3G) is received on SIM2. As the VoLTE call is active on SIM1, and a new MT CS call is received by the SIM2, then the active PS Voice call will be suspended or disconnected, as the CS voice call will be having higher precedence over the PS call. Currently there is no system and method available that can handle active PS voice call when the user equipment (UE) receives incoming CS call, while an active PS Voice (VoLTE/VoIP) call is ongoing.

Thus, there is a need for an optimized tune away system and method to handle active PS voice call during an incoming CS call in a Dual SIM Dual Standby (DSDS) configuration.

The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

SUMMARY OF THE INVENTION

The various embodiments herein disclose a method to handle incoming circuit switch (CS) call while voice over long term evolution or Voice over Internet Protocol (VoLTE/VoIP) call active in dual-SIM dual-standby (DSDS) case.

According to an embodiment of the present invention a method of handling MT Circuit switched call in Dual/Multi Sim Dual Stand-by (DSDS) Devices, comprises steps of checking, by a User Equipment, if a Voice over LTE/IP/(Ex: VoLTE/VoIP) call is active on a first SIM, performing a tune away to the first SIM if a CS call is detected for a second SIM, informing a user about incoming CS call on the second SIM, placing the VoLTE/VoIP call on the first SIM on hold, and processing the CS call by tuning away to the second SIM in a consecutive DRX cycle.

According to an embodiment of the present invention, the method further comprises of verifying if the user accepts the CS call on the second SIM, proceeding with the CS call if the user accepts the CS call, and resuming the VoLTE/VoIP call on the first SIM if the user rejects or terminates the accepted CS call.

According to another embodiment of the present invention, a method of handling MT Circuit switched call in Dual Sim Dual Stand-by (DSDS) Devices comprises steps of receiving, by a User Equipment (UE), a Circuit Switched (CS) call for a second SIM when a VoLTE/VoIP call is active on a first SIM, sending a Page response and starts a timer, checking if the timer is expired or not, rejecting the CS call if the timer is expired, transferring a transmission and reception control to a previous subscription, SUB, resuming the VoLTE/VoIP call on the first SIM1 and indicating a user about the missed CS call on the second SIM with a calling number.

According to an embodiment of the present invention, the T timer is configured for enabling the UE to recover VoLTE/VoIP call based on one or more network parameters. According to an embodiment of the present invention, the CS call is rejected with USER BUSY after receiving a CS call CC-SETUP message before the timer expiry. According to another embodiment of the present invention, the timer is a T300 timer.

According to an embodiment of the present invention, a method of handling MT Circuit switched call in Dual Sim Dual Stand-by (DSDS) Devices, comprises determining, by a User Equipment, whether a first SIM is configured for receiving a VoLTE/VoIP call, enabling a call forward with USER_BUSY to SIM1, receiving an indication of a Circuit Switched (CS) call on a second SIM, checking if the VoLTE/VoIP call is active on the first SIM when the CS call is received for the second SIM, and rejecting the CS call (USER BUSY) if the VoLTE/VoIP call is active on the first SIM.

According to yet another embodiment of the present invention, a method of handling MT Circuit switched call in Dual Sim Dual Stand-by (DSDS) Devices comprises determining, by a User Equipment (UE) if a VoLTE/VoIP call is active on a first SIM, receiving a Circuit Switched (CS) call for a second SIM when the VoLTE/VoIP call is active, and ignoring the CS call until the VoLTE/VoIP call on the first SIM is terminated.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a flow chart depicting a method for handling tune away for holding off a PS call during an ongoing MT CS call on SIM2 through auto call hold, according to an embodiment of the present invention.

Figure 2 is a schematic flow diagram depicting a method for handling tune away for holding off an IMS (VoLTE/VoIP) call during an ongoing MT CS call on SIM2 through auto call hold, according to an embodiment of the present invention.

Figure 3 is a flow chart depicting a method for handling tune away for continuing an Active VoLTE Call during an ongoing MT CS call on SIM2 through a missed call notification, according to an embodiment of the present invention.

Figure 4 is a schematic flow diagram depicting a method for handling tune away for continuing an Active VoLTE Call during an ongoing MT CS call on SIM2 through a missed call notification, according to an embodiment of the present invention.

Figure 5 is a flow chart depicting a method for handling tune away to continue with Active IMS Call on SIM1 during an ongoing MT CS call on SIM2 through auto call forward, according to an embodiment of the present invention.

Figure 6 is a schematic flow diagram depicting a method for handling MT CS call on SIM2 during an Active IMS Call on SIM1 through auto call forward, according to an embodiment of the present invention.

Figure 7 is a schematic block diagram illustrating user equipment (UE) that handles Mobile-Terminated (MT) Circuit Switched (CS) call, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method to handle incoming circuit switch (CS) call while voice over Internet or LTE (Long Term Evolution) protocol (VoLTE or VOIP) call active in dual/multi-SIM dual-standby (DSDS) case. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The present invention provides a method of handling an incoming circuit switch (CS) call when a Packet Switched (PS) call is active in a Dual SIM device in a Dual SIM Dual Standby (DSDS) mode. The present invention is described along with supporting use cases and embodiments to illustrate the working of the present methods, and the person having ordinarily skilled in the art can understand that the description of the present methods does not limit the scope of the present invention.

According to the present invention, the method of handling Mobile-Terminated (MT) Circuit Switched (CS) call in a Dual Subscriber Identity Module (Dual-SIM) device is described herein. The Dual SIM device can be any user equipment (UE) with capacity of receiving two or SIMs, using which the user can receive mobile terminating (MT) CS call, without departing from the scope of the invention. According to an embodiment of the present invention, the Dual SIM devices can include, but not limited to, mobile phone, tablet, and the like. Also, present invention is applicable to single SIM device where the OS Call is active and the MT CS Call is received. According to the present invention, the method comprises step of user equipment (UE) checking whether a packet-switched (PS) call is active on the first SIM. The UE comprises of two SIMs first SIM and second SIM. While the first SIM is active on packet switched (PS) call, the UE periodically checks whether the PS call is active on the first SIM or not. In an embodiment of the present invention, the PS call can be at least one of, but not limited to, VoLTE call, VoIP call, 2G/ 3G call, and the like. Therefore, the UE checks whether the VoLTE call or VoIP call is active on any of the SIMs.

Further, the method comprises step of detecting if a paging message is received for an incoming circuit-switched (CS) call on the second SIM. While the PS call is active on one SIM, the second SIM can be idle at that moment. But, periodically the second SIM has to check for its activity and checks if it has received any new data packets or CS calls. Thus, the UE can perform tune away to the first SIM such that the UE can periodically provide resources to the second SIM such that the second SIM can detect whether it is receiving any CS call or data packets, without affecting the ongoing active PS call.

Further, the method comprises the step of performing a tune-away to the first SIM if the paging message is received. If the UE identifies that the first SIM has received any paging messages, then the UE can tune-away from the second SIM to the first SIM, thereby allocating resources to the first SIM for addressing the paging message received by the first SIM.

Further, the method comprises steps of informing an IP multimedia Subsystem (IMS) of the incoming CS call on the second SIM. During tune away, if the second SIM identifies any incoming or MT CS call from the network based on the received paging message, then the second SIM can tune away the resources back to the first SIM and further, the UE can be inform the IP multimedia subsystem (IMS) about the MT CS call. Thus the user gets information about the incoming MT CS call. In an embodiment of the present invention, the information about the incoming CS call can be any notification that can include at least one of, but not limited to, vibration alert, blinking of the screen of the UE, audio alert such as beep tones, and the like.

Further, the method comprises step of placing the PS call on the first SIM on hold. Further, the method comprises the step of tuning away to the second SIM upon identifying that the MT CS call for the second SIM of the UE is being received. The MT CS call is given higher priority over the active PS call. But, the PS call is also important to the user, and therefore cannot be dropped intermittently. Therefore, the UE notifies the network about putting the active PS call on hold in favor of receiving the MT CS call. The active PS call can be put on hold so that the current active call should not be lost from the perspective of maintaining quality of service for the user.

Further, the method comprises step of processing the CS call by tuning away to the second SIM in a consecutive DRX cycle. According to an embodiment of the present invention, the method further comprises step of verifying if the user accepts the CS call on the second SIM. If the user accepts the CS call, then the method comprises step of proceeding with the CS call. If the user rejects or terminates the accepted CS call, then the method comprises step of resuming the PS call on the first SIM.

According to the present method, upon putting the PS call on hold, the UE processes the MT CS call, wherein the processing of the MT CS call comprises of tuning away the resources to the second SIM, the second SIM receiving the MT paging message from the network during next paging (DRX) cycle, acknowledging to the MT paging message with a PAGE RESPONSE message. Further, during processing of the MT CS call, the network can transmit CC-SETUP message for setting up the CS call with the UE. The second SIM can transmit CC-CALL CONFIRMED response message to the network for the receiving CC-SETUP message. Further, the network can transmit CC-ALERTING message to the second SIM, wherein the second SIM can transmit an alerting indication to the user about the MT CS call and thereby continuing with the CS call.

In an embodiment of the present invention, upon receiving the alerting indication about the CS call, the user of the UE can accept the CS call and continue being on the MT CS call and thereby continue keeping the PS call on hold. In another embodiment of the present invention, the user of the UE can disconnect the MT CS call upon receiving the alerting indication about the CS call. Upon rejecting the MT CS call, the PS call which is kept on hold can be switched to active state and the user of the UE can continue being on the active call state of the PS call. In an embodiment of the present invention, the present method can be applicable for single SIM device with VOIP Call active and CS call received case. Whenever the user equipment (UE) with single SIM is active on PS call and receives MT CS call, then the UE can identify the MT CS call, and can automatically put the PS call on hold.

According to an embodiment of the present invention, the method further comprises step of detecting if a paging message is received for the incoming circuit-switched (CS) call on the second SIM. The UE periodically detects if the paging message has been received for the MT CS call on the second SIM while the PS call is active on the first SIM. Further, the method comprises the step of performing a tune-away to the first SIM if the paging message is received for the incoming CS call on the second SIM. Upon identifying that the received paging message relates to the MT CS call on the second SIM, the UE tunes away the resources back to the first SIM on which the PS call is active.

Further, the method comprises step of checking if the PS call is active on the first SIM. The UE further continues PS call on the first SIM while the MT CS call is being received on the second SIM. Further, the method comprises step of sending a user busy notification as a paging response. As the PS call is still active on the first SIM, the UE gives higher precedence to the active call than the MT CS call, and thus sends a busy notification as the paging response to the paging message received for the second SIM from the user. In an embodiment of the present invention, the busy notification can be any one of, but not limited to, busy tone, voice message indicating user busy on another call, and the like.

Further, the method comprises the step of forwarding the CS call to the first SIM. Upon sending busy notification for the MT CS call, the UE can also forward information about the CS call to the first SIM. Further, the method comprises step of sending a call forward notification to the user. As the information about the CS call is forwarded to the first SIM, the first SIM can provide the information to the user. In an embodiment of the present invention, the forwarding/ providing information to the user about MT CS call can include, but not limited to, vibration, ring tone, flash message, SMS and the like. According to the present invention, the active PS call is given the higher precedence/ priority over the MT CS call and thus allowed to continue the PS call without dropping it upon receiving the MT CS call.

According to another embodiment of the present invention, the method further comprises step of determining, if the PS call is active on the first SIM. Further, the method comprises step of receiving the paging message for the CS call on the second SIM. Further, the method comprises step of ignoring the CS call until the PS call on the first SIM is terminated.

Figure 1 is a flow chart 100 depicting a method for handling tune away for holding off PS call during an incoming MT CS call on SIM2 through auto call hold, according to an embodiment of the present invention. According to the Figure. 1, upon receiving the MT CS call on second SIM SIM2, the UE can put the ongoing active PS call on SIM1 on hold so that the MT CS call on SIM2 is given higher priority and handled at higher precedence. According to the flow chart 100, the present flow chart describes about the user equipment (UE) with dual SIM dual standby (DSDS) capability, wherein one SIM out of the two SIMs the first SIM SIM1 and the second SIM SIM2 can be active at one time and the other SIM will be in idle mode. According to the flow chart 100, at step 102, the UE checks whether the tune away feature is enabled for first SIM SIM1. If the tune away feature is enabled, then at step 104, the UE detects whether the active PS call is ongoing on the first SIM SIM1 or not. If no, then the UE can periodically detect for the active PS call.

If yes, then at step 106, the UE checks whether the second SIM SIM2 has received the MT CS paging message for the MT CS call from network. If yes, then at step 108, the UE tunes away resources to first SIM SIM1 by not responding to paging message from the network. At step 110, the UE receives information about the MT CS call on second SIM SIM2 and therefore based on the received information, the UE puts the active PS call on hold. At step 112, the UE tunes away resources to second SIM SIM2 and processes next paging message in DRX cycle. At step 114, the UE processes the MT CS call.

At step 116, the UE checks whether the user of the UE accepts the call or not. If yes, then at step 118, the UE can continue being on the MT CS call with PS call on hold. If the user of the UE does not accept the MT CS call, then at step 120, the PS call of the first SIM SIM1 can be resumed. At step 122, the UE checks whether the MT CS call is ended. If yes, then the process moves to step 120 wherein the PS call which was on hold can be resumed.

Figure 2 is a schematic flow diagram 200 depicting a method for handling tune away for holding off a PS call during an ongoing MT CS call on SIM2 through auto call hold, according to an embodiment of the present invention. According to the Figure 2, the flow diagram illustrates how a user equipment (UE) 202 having two SIMs SIM1 204 and SIM2 206 handles MT CS call on one SIM while an ongoing PS call on another SIM. The Figure 2 further comprises of a network 208 for transmission and reception of messages.

According to the flow diagram 200, the UE 202 is active on the SIM1 204 over a PS. The SIM1 204 transmits a status message to the network 208 indicating that the PS call is active on the SIM1 204. Further, the SIM1 204 tunes away the resources to SIM2 206 for paging activities. Further, the network transmits MT PAGE message to the SIM2 206. After receiving the MT PAGE message from the network 208, the SIM2 206 tunes away the resources back to SIM1 204. Further, the SIM1 204 informs the UE 202 about the received MT PAGE on the SIM2 206.

Based on the received MT PAGE message, the UE 202 puts the PS call of the SIM1 204 on hold. Further, the SIM1 204 tunes away the resources to the SIM2 206. Further, the network 208 transmits MT PAGE message to the SIM2 206 in the next DRX cycle. For the received MT PAGE message, the SIM2 206 transmits PAGE RESPONSE message to the network 208 as response to the received message. Further, the network 208 transmits CC-SETUP message to the SIM2 206. Further, the SIM2 206 transmits the CC- CALL CONFIRMED message to the network 208. Further, the network 208 transmits the CC- ALERTING message to the SIM2 206. Further, the SIM2 206 transmits a message to the UE 202 alerting an indication user about the incoming MT CS call. Based on the alert about the incoming MT CS call, the user can receive/ accepts the call or reject the call. If the user accepts the call, then the PS call will be continued to be hold. If the user rejects the MT CS call, then the PS call can resume.

According to another embodiment of the present invention, a method of handling Mobile-Terminated (MT) Circuit Switched (CS) call in a Dual Subscriber Identity Module (Dual-SIM) device comprises step of a user equipment (UE) receiving a paging message for a Circuit Switched (CS) call for the second SIM when a Packet Switched (PS) call is active on the first SIM. The UE is a dual SIM device, wherein the first SIM is handling the active PS call. The UE receives the MT CS call on second SIM. Further, the method comprises of UE tunes away the resources to the second SIM from first SIM periodically for checking any incoming data packets or calls.

Further, the method comprises step of sending a response for the paging message and initiates a timer. During tune away, the second SIM receives the MT CS call, wherein a network informs the second SIM about the MT CS call by sending MT page information to the second SIM. Upon receiving the MT page message, the second SIM can transmit the page response. As soon as the page response is transmitted, the UE can start the timer. In an embodiment of the present invention, the timer is configured for enabling the UE to recover PS call based on one or more network parameters. In another embodiment of the present invention, the timer can be a T300 timer. In another embodiment of the present invention, the timer can be any of the known timers used for measuring the time taken by the network to respond to the page response of the second SIM, without departing from the scope of the invention.

Further, the method comprises step of checking if a CS call set up message for the second SIM is received before the timer expiry. The UE checks whether the set up message for setting up of the MT CS call has been received by the second SIM before expiration of the timer or not. Further, the method comprises step of transferring a transmission-reception control of the CS call to a sub-station on which the PS call is initiated if the CS call set up message is not received before the timer expiry. Upon expiry of the timer, the UE can transfer the transmission-reception control of the CS call to a sub-station on which the PS call is initiated.

Further, the method comprises step of rejecting the CS on the second SIM. The UE can wait till the expiry of the timer. If the UE does not receive any response from the network before expiry of the timer, the UE can reject the CS call as soon as the timer gets expired. In an embodiment of the present invention, the CS call is rejected after receiving a CS call CC-SETUP message before the timer expiry.

Further, the method comprises step of resuming the PS call on the first SIM1. Upon identifying that the UE has not received any response from the network before timer expiry, the UE can switch back to the first SIM, and resume the PS call on the first SIM before experiencing radio link failure (RLF) before expiry of the timer.

Further, the method comprises step of indicating a user about the missed CS call on the second SIM. The user of the UE can receive the notification from the UE that user has received the missed CS call on the second SIM along with the calling number. In an embodiment of the present invention, the method comprises step of indicating the user of the missed incoming CS call on the second SIM along with a calling number, if the CS call set up message is received before the timer expiry. In an embodiment of the present invention, the notification can be at least one of, but not limited to, a flash message on the display of the UE, a SMS, and the like. The various types of notifications can be used for indicating the user about the missed CS call on the second SIM, without departing from the scope of the invention.

Figure 3 is a flow chart 300 depicting a method for handling tune away for continuing an Active PS Call during an ongoing MT CS call on SIM2 through a missed call notification, according to an embodiment of the present invention. According to the flow chart 300, at step 302, the UE checks whether the tune away feature is enabled for first SIM SIM1. If the tune away feature is enabled, then at step 304, the UE detects whether the active PS call is ongoing on the first SIM SIM1 or not. If no, then the UE can periodically detect for the active PS call.

If yes, then at step 306, the UE checks whether the second SIM SIM2 has received the MT CS paging message for the MT CS call from network. If yes, then at step 308, the second SIM SIM2 transmits the paging response message to the network and starts the timer. At step 310, the UE checks whether MT SETUP message is received by the network or timer expired. If yes, then at step 312, the UE Transfer the reception and transmission control to previous subscription, SUB by rejecting MT CS Call.

At step 314, the UE recovers from radio link failure (RLF) in LTE and PS call will resume. At step 316, the user of the UE is notified about MT CS Call with Number if MT SETUP message is received. At step 318, the UE checks whether PS call is ended or not. If yes, then the process moves to step 304, wherein the UE checks whether the PS call is detected or not. If no, then the process moves to step 306, wherein the UE checks whether the MT CS paging message is received.

Figure 4 is a schematic flow diagram 400 depicting a method for handling tune away for continuing an Active PS Call during an ongoing MT CS call on SIM2 through a missed call notification, according to an embodiment of the present invention. According to the Figure 4, the flow diagram 400 illustrates how a user equipment (UE) 402 having two SIMs SIM1 404 and SIM2 406 handles MT CS call on one SIM while an ongoing PS on another SIM. The Figure 4 further comprises of a network 408 for transmission and reception of messages.

According to the flow diagram 400, the UE 402 is active on the SIM1 404 over a PS call. Further, the SIM1 404 tunes away the resources to SIM2 406 for paging activities. Further, the network transmits MT paging message to the SIM2 406. After receiving the MT paging message from the network 408, the SIM2 406 transmits paging response message to the network 408. Further, the network 408 transmits CC-SETUP message to the SIM2 406. Upon receiving the CC-SETUP message, the SIM2 406 transmits CC-RELEASE message to the network 408.

Upon transmitting the message to the network 408, the SIM2 406 tunes away resources back to the SIM1 404. Upon receiving the resources, the PS call resumes on SIM1 404. Further, the UE 402 receives indication about missed call for the received MT CS call along with the number.

According to another embodiment of the present invention, a method of handling Mobile-Terminated (MT) Circuit Switched (CS) call in a Dual Subscriber Identity Module (Dual-SIM) device comprises step of a user equipment (UE) determining whether a first SIM is configured for receiving a PS call. The UE comprises of dual SIMs wherein the first SIM determines whether it is configured to receive the PS call or not.

Further, the method comprises step of the UE enabling a call forward with USER_BUSY to first SIM. Upon identifying that the first SIM can receive the PS call, the UE can enable call forwarding (USER BUSY) option for the first SIM, wherein if the UE is receiving any MT CS call on SIM2 while PS call is active on the first SIM, then the SIM2 CS call can be forwarded along with the USER BUSY message.

Further, the method comprises step of receiving an indication of a Circuit Switched (CS) call on a second SIM. During the ongoing active PS call, the UE receives an indication of an incoming or mobile terminating (MT) CS call on the second SIM. According to the present invention, various indications for receiving the MT CS call are described with respect to herein abovementioned embodiments, and hence not described again to avoid repetition.

Further, the method comprises step of checking if the PS call is active on the first SIM when the CS call is received for the second SIM. The UE checks whether the PS call is still active while the UE is receiving the MT CS call. Any of the process for checking the active PS call while receiving the MT CS call, known to the person having ordinarily skilled in the art can be used without departing from the scope of the invention.

Further, the method comprises step of rejecting the CS call if the PS call is active on the first SIM. If the PS call is active, then the UE can give higher precedence to the ongoing PS call on the first SIM and can reject the MT CS call on the second SIM with cause USER BUSY.

In another embodiment of the present invention, the method further comprises of forwarding the CS call to the first SIM when the PS call is active. Further, the method comprises of sending a call forward notification to the user, thereby the user can receive the forwarded call on the SIM SIM1 on which PS call is active. In this case incoming call is based on the call waiting feature, user has option to receive the incoming call similar to call waiting functionality in single SIM devices.

Figure 5 is a flow chart 500 depicting a method for handling tune away to continue with Active IMS Call on SIM1 during an ongoing MT CS call on SIM2 through auto call forward, according to an embodiment of the present invention. According to the flow chart 300, at step 302, the UE checks whether the tune away feature is enabled for first SIM SIM1. If the tune away feature is enabled, then at step 304, the UE detects whether it is possible to have PS call on first SIM SIM1. If yes, then upon receiving MT CS call on second SIM SIM2, at step 306, MT CS call of the second SIM SIM2 can be forwarded to the first SIM SIM1 informing to the caller as user is busy. At step 308, UE checks whether MT CS PAGE received on the second SIM SIM2. If yes, then at step 310, the UE further checks whether PS call is active on the first SIM SIM1. If yes, then at step 312, the UE sends any Call Control message to the network as user busy. Further, at step 314, the MT CS call can be forwarded to the first SIM SIM1 of the UE and the MT CS call can be notified to the user of the UE.

According to another embodiment of the present invention, a method of handling Mobile-Terminated (MT) Circuit Switched (CS) call in a Dual Subscriber Identity Module (Dual-SIM) device comprises step of a User Equipment (UE) determining if a PS call is active on a first SIM. The UE can identify whether any PS call is active on the first SIM based on the resources allocated to the first SIM for participating in the PS call.

Further, the method comprises step of receiving a Circuit Switched (CS) call for a second SIM when the PS call is active. When the PS call is active on the first SIM, the second SIM of the UE receives the MT CS call. Further, the method comprises step of ignoring the CS call until the PS call on the first SIM is terminated. The MT CS call can be ignored and no indication or notification is provided to the user of the UE. Once the active PS call gets over, the notification about MT CS call can be provided to the UE.

Figure 6 is a schematic flow diagram depicting a method for handling MT CS call on SIM2 during an Active Call on SIM1 through auto call forward, according to an embodiment of the present invention. According to the Figure 6, the flow diagram 600 illustrates how a user equipment (UE) 602 having two SIMs SIM1 604 and SIM2 606 handles MT CS call on one SIM while an ongoing PS on another SIM. The Figure 6 further comprises of a network 608 for transmission and reception of messages.

According to the flow diagram 600, the UE 602 is active on the SIM1 604 over a PS call. The SIM1 604 transmits a status message to the network 608 indicating that the PS call is active on the SIM1 604. Further, the SIM1 604 tunes away the resources to SIM2 606 for paging activities. Further, the network transmits MT PAGE message to the SIM2 606. After receiving the MT PAGE message from the network 608, the SIM2 606 checks whether the VoLTE call on the SIM1 604 is active. If yes, then the SIM2 606 tunes away resources back to the SIM1 604, and thereby the PS call resumes on the SIM1 604.

According to another embodiment of the present invention, a user equipment for handling Mobile-Terminated (MT) Circuit Switched (CS) call comprises of a first subscriber identity module (SIM), wherein the first SIM is associated with at least one network, and a second subscriber identity module (SIM), wherein the second SIM is associated with at least one network. According to an embodiment of the present invention, the UE can be a Dual SIM Dual Standby (DSDS) device. According to another embodiment of the present invention, the UE can be multi SIM device that can comprise more than two SIMs which can be operated by one or more networks, without departing from the scope of the present invention.

Further, the UE comprises a communication unit adapted for checking whether a packet-switched (PS) call is active on the first SIM. Further, the communication unit can detect if a paging message is received for an incoming circuit-switched (CS) call on the second SIM. Further, the communication unit can perform a tune-away to the first SIM if the paging message is received. Further, the communication unit informs an IP multimedia Subsystem (IMS) of the incoming CS call on the second SIM. Further, the communication unit places the PS call on the first SIM on hold. Further, the communication unit tunes away to the second SIM and processes the incoming CS call.

According to another embodiment of the present invention, the communication unit can further checks if the PS call is active on the first SIM, sends a user busy notification as a paging response, forwards the CS call to the first SIM, and sends a call forward notification to the user.

Figure 7 is a schematic block diagram illustrating user equipment (UE) 700 that handles Mobile-Terminated (MT) Circuit Switched (CS) call, according to an embodiment of the present invention. According to the present invention, the UE 700 can be a Dual SIM Dual Standby (DSDS) device. According to the diagram, the UE 700 comprises a first subscriber identity module (SIM) 702, and a second subscriber identity module (SIM) 704, and a communication unit 706. In an embodiment of the present invention, the first SIM 702 and the second SIM 704 can be associated with same network. In another embodiment of the present invention, the first SIM 702 and the second SIM 704 can be associated with different networks, without departing from the scope of the invention.

The communication unit 706 checks whether a packet-switched (PS) call is active on the first SIM, detects if a paging message is received for an incoming circuit-switched (CS) call on the second SIM, performs a tune-away to the first SIM if the paging message is received, informs an IP multimedia Subsystem (IMS) of the incoming CS call on the second SIM, places the PS call on the first SIM on hold, tunes away to the second SIM and processes the incoming CS call. The UE 700 further comprises of a display 708 for displaying alert to the user about MT CS call on second SIM while the user is active with PS call on first SIM.

Further, the UE 700 comprises an audio unit 710 that can generate audio alerts such as, but not limited to, ring tones, vibrations, beep tones and the like to the user for informing user about the MT CS call.

The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Furthermore, the various devices, modules, and the like described herein may be enabled and operated using hardware circuitry, for example, complementary metal oxide semiconductor based logic circuitry, firmware, software and/or any combination of hardware, firmware, and/or software embodied in a machine readable medium. For example, the various electrical structure and methods may be embodied using transistors, logic gates, and electrical circuits, such as application specific integrated circuit.

Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

,CLAIMS:ABSTRACT

The various embodiments herein disclose a method of handling Mobile-Terminated (MT) Circuit Switched (CS) call in a Dual Subscriber Identity Module (Dual-SIM) device. The method comprising checking, by a User Equipment (UE), including a first SIM and a second SIM, whether a packet-switched (PS) call is active on the first SIM, detecting if a paging message is received for an incoming circuit-switched (CS) call on the second SIM, performing a tune-away to the first SIM if the paging message is received, informing an IP multimedia Subsystem (IMS) of the incoming CS call on the second SIM, placing the PS call on the first SIM on hold, tuning away to the second SIM and processing the incoming CS call.

Figure 3