Method and system for establishing voice call

Abstract

The present disclosure relates to a method and system for establishing a voice call. The method comprises: detecting initiation of a voice call procedure for establishing a voice call between a first user equipment [102] and a second user equipment [104]; selecting a low generation radio access technology based on initiation of the voice call procedure; transmitting a tracking area update (TAU) request and a radio resource control (RRC) connection request, where the RRC connection request includes a cause message; detecting the initiation of a TAU procedure based on the RRC connection establishment through the cause message; detecting establishment of default bearers of an Internet Protocol Multimedia Subsystem (IMS) and a Public Data Network (PDN); receiving an activation dedicated bearer request for the voice call based on IMS and PDN default bearers; detecting a dedicated bearer; and establishing a voice call based on the dedicated bearer.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to voice calls in fifth generation (5G) mobile communication networks, and more particularly, to a method and system for avoiding voice call failure and establishing a voice call on user equipment in case of Radio Resource Control (RRC) Release with redirection (RWR) failure and / or 5QI=1 (i.e., 5G Quality of Service Identifier = 1) Packet Data Unit (PDU) modification failure. BACKGROUND

[0002] The following description of related art is intended to provide background information on the field of the disclosure. This section can include some aspects of the technology that can be related to various features of the present disclosure. However, it is understood that this section is only intended to enhance the reader's understanding of the present disclosure, and not to acknowledge prior art.

[0003] In 5G networks, for Internet Protocol Multimedia Subsystem (IMS) stack, there is an option to work on Voice over New Radio (VoNR). Another way to establish a voice call is to fallback to 4G network, i.e., Voice over Long Term Evolution (VoLTE) by redirecting the user equipment (UE) or user device (UD) to Long Term Evolution (LTE) i.e., 4G network for voice call, which is known as EPS Fallback (EPSFB). For this, most network providers provide both VoNR and EPSFB options for voice call. EPSFB calls, i.e., calls after fallback to lower Radio Access Technology (RAT) have to be properly maintained by the network provider and the UE. When 5G network coverage is weak in the area, or in case of network or user equipment not supporting VoNR, fallback to lower generation RAT (e.g., 4G or 3G) is the only option for establishing a voice call, which is initiated by the network for making the UE fallback to lower generation RAT, e.g., LTE, via RWR command to continue the call creation. However, in case of EPSFB calls, RWR failure, if any, can cause call creation failure. Further, in case of VoNR calls, 5QI=1 Packet Data Unit (PDU) modification command failure can also occur. This can result in voice call failure and poor user experience.

[0004] Therefore, there is an urgent need to develop a solution that can be provided to a user equipment for creating a voice call in case of network failure for RRC release with redirection (RWR) or 5QI=1 (i.e., 5G Quality of Service Identifier = 1) packet data unit (PDU) modification failure. This would help users have a better experience in terms of establishing a voice call when in a weak 5G network or when the user's user equipment does not support voice call features on an advanced RAT network and reducing call failures. Further, this can also help optimize the registration of the user equipment to the network and can also help improve the battery efficiency of the user equipment. SUMMARY

[0005] This section provides a simplified introduction to some of the purposes and aspects of the present invention, which are further described in the detailed description below. This summary is not intended to identify key features or the scope of the claimed subject matter.

[0006] A first object of the present disclosure is to provide a method and system for establishing a voice call on a user equipment that overcomes the limitations of the existing methods.

[0007] Another object of the present disclosure is to provide a method and system for establishing a voice call on a user equipment that is capable of creating a voice call in case of network failure for RRC release with redirection (RWR) or 5QI=1 (i.e., 5G Quality of Service Identifier = 1) packet data unit (PDU) modification failure.

[0008] Yet another object of the present disclosure is to provide a method and system for establishing a voice call on a user equipment that is helpful in at least the following aspects: 1) reducing voice call failures on a user equipment, 2) optimizing key performance indicators (KPIs) of a network by optimizing faster registration of a user equipment to the network, and 3) improving the battery efficiency of a user equipment.

[0009] To achieve at least one of the above-mentioned objects, one aspect of the present application can relate to a method for establishing a voice call. The method includes detecting, by a processing unit at a first user equipment, initiation of a voice call procedure for establishing a voice call between the first user equipment and a second user equipment via a network entity. Further, the method includes selecting, by the processing unit at the first user equipment, a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure. The method also includes sending, by the processing unit from the first user equipment to the network entity, a tracking area update request and a radio resource control (RRC) connection request in response to the selection of the low generation RAT, wherein the RRC connection request includes a cause message. The method further includes detecting, by the processing unit at the first user equipment, initiation of a tracking area update procedure based on RRC connection setup by the cause message. Moreover, the method includes detecting, by the processing unit at the first user equipment, establishment of an internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity. The method also includes receiving, by the processing unit at the first user equipment, an activate dedicated bearer request for the voice call from the network entity based on the IMS and the one or more PDN default bearers. Further, the method includes detecting, by the processing unit for the first user equipment, a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request. Finally, the method includes establishing, by the processing unit, the voice call between the first user equipment and the second user equipment based on the dedicated bearer.

[0010] Another aspect of the disclosure relates to a system for establishing a voice call. The system includes a processing unit. The processing unit is configured to detect, at a first user equipment, initiation of a voice call procedure for establishing a voice call between the first user equipment and a second user equipment via a network entity. Further, the processing unit is configured to select, at the first user equipment, a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure. Further, the processing unit is configured to send, from the first user equipment to the network entity, a tracking area update request and a radio resource control (RRC) connection request in response to the selection of the low generation RAT, wherein the RRC connection request includes a cause message. Further, the processing unit is configured to detect, at the first user equipment, initiation of a tracking area update procedure based on RRC connection establishment by the cause message. The processing unit is also configured to detect, at the first user equipment, establishment of an internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity. Further, the processing unit is configured to receive, at the first user equipment from the network entity, an activate dedicated bearer request for the voice call based on the IMS and the one or more PDN default bearers. Further, the processing unit is configured to detect, for the first user equipment, a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request. Further, the processing unit is configured to establish the voice call between the first user equipment and the second user equipment based on the dedicated bearer.

[0011] Yet another aspect of the disclosure can relate to a first user device for establishing a voice call. The first user device includes a system. The system further includes a processing unit. The processing unit is configured to detect, at the first user device, initiation of a voice call procedure for establishing a voice call between the first user device and a second user device via a network entity. Further, the processing unit is configured to select, at the first user device, a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure. Further, the processing unit is configured to send, from the first user device to the network entity, a tracking area update request and a radio resource control (RRC) connection request in response to the selection of the low generation RAT, wherein the RRC connection request includes a cause message. Further, the processing unit is configured to detect, at the first user device, initiation of a tracking area update procedure based on RRC connection establishment by the cause message. The processing unit is further configured to detect, at the first user device, establishment of an internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity. Further, the processing unit is configured to receive, at the first user device, an activate dedicated bearer request for the voice call from the network entity based on the IMS and the one or more PDN default bearers. Further, the processing unit is configured to detect, for the first user device, a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request. Further, the processing unit is configured to establish the voice call between the first user device and the second user device based on the dedicated bearer. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and constitute a part of the disclosure, illustrate exemplary implementations of the disclosed methods and systems, in which like reference numerals refer to similar parts throughout the various drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Additionally, implementations shown in the figures should not be interpreted to limit the present disclosure, but rather the possible variations of the methods and systems according to the present disclosure are shown herein to highlight the advantages of the present disclosure. Some of the drawings can use block diagrams to indicate components, and can not represent the internal circuitry of each component. Those skilled in the art will understand that the disclosure of such figures includes the disclosure of electrical components, electronic components, or circuitry generally used to implement such components.

[0013] Figure 1 An exemplary block diagram depicting an exemplary network architecture diagram

[100] is shown in accordance with implementations of the present disclosure.

[0014] Figure 2 An exemplary block diagram of a system

[200] for establishing a voice call between a first user device and a second user device is shown in accordance with implementations of the present disclosure.

[0015] Figure 3 An exemplary method flow diagram

[300] for establishing a voice call between a first user device and a second user device is shown in accordance with an embodiment of the present disclosure.

[0016] Figure 4 A detailed exemplary flow diagram of a method for establishing a voice call between a first user device and a second user device is shown in accordance with an exemplary embodiment of the present disclosure.

[0017] The foregoing will be more readily understood in consideration of the following more detailed description of the present disclosure. DETAILED DESCRIPTION

[0018] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent, however, that embodiments of the present disclosure can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the underlying principles of the embodiments described.

[0019] The ensuing description provides exemplary embodiments only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an exemplary embodiment. It should be understood that various changes can be made in the function and arrangement of elements without departing from the spirit and scope of the disclosed embodiments. There has thus been outlined, rather broadly, the more important features of the disclosure in order that the detailed description thereof can be better understood, and in order that the present contribution to the art can be better appreciated.

[0020] In the following description, specific details are set forth to provide a thorough understanding of the embodiments. However, one having ordinary skill in the art will understand that the embodiments can be practiced without the specific details. For example, circuits, systems, processes and other components can be shown as components in block diagram form, in order not to obscure the embodiments in unnecessary detail.

[0021] Additionally, it should be noted that various embodiments can be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart can describe operations as a sequential process, many of the operations can be performed in parallel, or concurrently, or in any order. In addition, the order of the operations can be re-arranged. A process is terminated when its operations are completed, but could be terminated before, by exception or error. Processes described can be implemented within or performed by discrete components or within applications stored on one or more computer readable media or by a combination thereof.

[0022] The words “exemplary” and / or “demonstrative” are used herein to mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by such examples. In addition, any aspect or design described herein as “exemplary” and / or “demonstrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to preclude equivalent exemplary structures and techniques known to those of ordinary skill in the art. Furthermore, to the extent that the terms “includes,” “has,” “contains,” and other similar words are used in either the detailed description or the claims, such terms are always intended to be inclusive in a manner similar to the term “comprising” as an open transition term without precluding any additional or other elements.

[0023] As used herein, a “processing unit” or “processor” or “operational processor” includes one or more processors, where a processor refers to any logic circuitry that processes instructions. The processor can be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor, a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an application specific integrated circuit, a field programmable gate array circuit, any other type of integrated circuit, and the like. The processor can perform signal coding data processing, input / output processing, and / or any other function that enables the system according to the present disclosure to operate. More specifically, the processor or processing unit is a hardware processor.

[0024] As used herein, “user equipment,” “user device,” “smart user equipment,” “smart device,” “electronic device,” “mobile device,” “handheld device,” “wireless communication device,” “mobile communication device,” “communication device,” “first user equipment,” and “second user equipment” can be any electrical, electronic, and / or computing device or apparatus that is capable of implementing the features of the present disclosure. The user equipment / user device can include, but is not limited to, a mobile phone, a smart phone, a laptop computer, a general purpose computer, a desktop computer, a personal digital assistant, a tablet computer, a wearable device, or any other computing device capable of implementing the features of the present disclosure. Additionally, the user equipment can contain at least one input device configured to receive input from at least one of a transceiver unit, a processing unit, a storage unit, and any other such unit necessary to implement the features of the present disclosure.

[0025] Currently, when a user equipment registers to a 5G network for 5G data service for mobile originating (MO) call and / or mobile terminating (MT) call, the Internet Protocol Multimedia Subsystem (IMS) Session Initiation Protocol (SIP) signaling starts in 5G without a dedicated bearer. After 183 session progress, there are two methods for establishing a voice call:

[0026] 1. In an evolved packet system (EPS) fallback method, the network sends a RWR command to the user equipment to fallback to a low radio access technology (RAT) network (such as 3G or 4G in case 5G is a high RAT) and establishes a dedicated bearer in the low RAT to establish a voice call through a real-time transport protocol (RTP) packet flow.

[0027] 2. In a new radio voice bearer (VoNR) method, the network sends a 5QI=1 (i.e., 5G quality of service identifier = 1) packet data unit (PDU) modification and dedicated bearer creation to do session initiation protocol (SIP) signaling to establish a voice call and successful real-time transport protocol (RTP) flow.

[0028] However, there are issues related to RWR failure and / or 5QI=1 PDU modification failure, latency due to configuration, Xn handover, network failure in 5G, and weak 5G coverage, etc. For example, when there is a latency of more than 6 seconds, the call creation can fail in case the telecommunication application server (TAS) in the IMS infrastructure has a 6 second timeout as per the request for comments (RFC) specification. For example, according to the RFC 3261 specification, the call creation will fail when there is a latency of more than 6 seconds, as per the RFC specification, the TAS in the IMS infrastructure has a 6 second timeout in case of a Non-Invite SIP signaling message with a retry every 2 seconds consecutively, and a 14 second timeout in case of an Invite SIP message with a retry three times of 2 seconds, followed by 4 seconds, and then another 8 seconds. In case of 5G network failure or poor 5G coverage, there can be a call creation failure and the user equipment can need to be handed over to 4G or 3G and restricted for 5G data service. In such a case, there can be a higher call creation failure resulting in a poor user experience and network key performance indicator (KPI) degradation.

[0029] The present disclosure relates to a system and method for establishing a voice call between a first user equipment and a second user equipment. The present invention provides a method and system that enables a user equipment (UE), i.e. a first user equipment, to switch to a low RAT, such as LTE coverage, using the UE's internally defined timer through a reselection mechanism in case the UE fails to receive a RWR command (in case of EPS FB method) or a 5QI=1 PDU modification command (in case of VoNR method) within a predefined time period. For the purpose of the present disclosure, the skilled person will understand the term "PDU modification" as a PDU modification for 5 QI=1 and the term "PDU modification bearer" as a PDU modification bearer for 5 QI=1 as commonly used in the art, however, the present disclosure is not limited to a specific communication network and related terminology and can be implemented for other communication networks in a manner apparent to the skilled person. The UE already has a reselection RAT with band information from system information block type 5 (SIB5) stored internally by the UE. After reselection to the low RAT, the UE initiates a tracking area update (TAU) request along with a radio resource control (RRC) connection request with "cause - mo voice call / mt access". The RRC connection creation with "cause - mo voice call / mt access" causes the network to create a dedicated bearer (e.g. QCI 1) for the UE. Thereby, the voice call setup procedure along with the real-time transport protocol (RTP) and real-time transport control protocol (RTCP) packet flow happens without any latency.

[0030] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, so that those skilled in the art to which the present disclosure pertains can easily practice the present disclosure.

[0031] Referring to Figure 1 , Figure 1 An exemplary block diagram depicting an exemplary network architecture diagram

[100] is shown in accordance with an exemplary embodiment of the present disclosure. As shown in Figure 1 , the exemplary network architecture diagram

[100] includes at least one first user equipment

[102] connected to at least one second user equipment

[104] via at least one network / network entity

[106] , wherein in an implementation, a system

[200] is present in the first user equipment

[102] and communicates with the network

[106] via a communication means

[204] .

[0032] Additionally, in Figure 1In the drawings, only a single first user equipment (or can be referred to as user equipment)

[102] , a single network

[106] and a single second user equipment

[104] are shown, however, there can be multiple such first user equipment

[102] , second user equipment

[104] and / or networks

[106] or any such number of said first user equipment

[102] , second user equipment

[104] and / or networks

[106] as would be apparent to the skilled person or as required for implementing features of the present disclosure.

[0033] Figure 2 An exemplary overview of components of a system

[200] for establishing a voice call between a first user equipment

[102] and a second user equipment

[102] according to an exemplary embodiment of the present application is shown. The system

[200] comprises a processing unit

[202] and a communication device

[204] and it is assumed that all components of the system

[200] are connected to each other until otherwise indicated in the present disclosure.

[0034] With reference to Figure 2 The processing unit

[202] detects an initiation of a voice call procedure for establishing a voice call between the first user equipment

[102] and the second user equipment

[104] via a network entity

[106] . The voice call procedure is for handling call failures, i.e. for avoiding call failures. The voice call procedure can be implemented in particular to avoid call failures in case of a network failure for RRC release with redirection (RWR) or 5QI=1 (i.e. 5G Quality of Service Identifier = 1) packet data unit (PDU) modification failure.

[0035] In an embodiment, prior to detecting the initiation of the voice call procedure for establishing a voice call between the first user equipment

[102] and the second user equipment

[104] via the network entity

[106] , the processing unit

[202] initiates an invitation message for the voice call. For example, to initiate an invitation message for a mobile originating (MO) / mobile terminating (MT) voice call, the user equipment (UE) initiates an invite (INVITE) message with a private-access network information (P-ANI) header for "3GPP-NR-FDD / TDD" and session description protocol (SDP) content with an enhanced voice service (EVS) audio codec. With this initiation, the network entity

[106] sends a "183 session in progress" message to the user equipment. In other words, the processing unit

[202] receives a session-in-progress message at the first user equipment

[102] from the network entity

[106] . As is generally known in the art, the "183 session in progress" message provides a header and media that can be used to convey information about the voice call.

[0036] Further, the processing unit

[202] initiates a counter-timer at the first user device

[102] for a predefined time period. The counter-timer is initiated for receiving one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period. In a preferred implementation, the predefined time period is 3000 milliseconds (ms). In other implementations, the predefined time can be in the range of 2000 ms to 3500 ms. Additionally, in an implementation, the counter-timer is initiated at the IMS layer of the first user device

[102] .

[0037] Further, the processing unit

[202] is configured to detect at the first user device

[102] an indication of one of successful reception and unsuccessful reception of one of a packet data unit (PDU) modify bearer (e.g., 5QI=1 / PDU modify bearer) and a RRC release with redirection (RWR) command within the predefined time period. In case of VoNR, 5 QI=1 / PDU modify bearer is expected to be received from the network, and in case of EPSFB, RRC release with redirection (RWR) is expected to be received from the network. Here, in case the processing unit

[202] detects an indication of successful reception of one of a packet data unit (PDU) modify bearer in case of VoNR within the predefined time period and an indication of successful reception of a RRC release with redirection (RWR) command in case of EPS fallback within the predefined time period, the voice call can be established between the first user device

[102] and the second user device

[104] via the network entity

[106] by following the standard procedure. However, in an implementation, in case the processing unit

[202] detects an indication of unsuccessful reception of one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period, the processing unit

[202] initiates a voice call procedure based on the unsuccessful reception. In an example, the PDU modify bearer (e.g., 5QI=1 / PDU modify bearer) or the RWR can not be received by the first user device

[102] due to network failure or any other reason. Additionally, the voice call procedure is a procedure that enables to avoid voice call failure and establish the voice call even when the first user device

[102] does not receive the 5QI=1 / PDU modify bearer or the RWR command within the predefined time period, like for example, 3000 ms, after which the counter-timer expires.

[0038] Accordingly, the processing unit

[202] detects initiation of a voice call procedure for establishing a voice call between the first user device

[102] and the second user device

[104] via the network entity

[106] upon expiry of the counter-timer after not receiving the 5QI=1 / PDU modified bearer or the RWR command.

[0039] Upon detecting initiation of the voice call procedure, the processing unit

[202] selects a low generation radio access technology (RAT) at the first user device

[102] . The low generation RAT can be any previous generation of mobile communication as compared to the latest generation RAT through which the first user device

[102] is connected to the network entity

[106] . For example, the first user device

[102] is connected to the network entity

[106] through a 5G (i.e., fifth generation) network. Accordingly, the low generation RAT can be 4G, 3G and 2G (i.e., fourth, third and second generation mobile communications as generally known in the art). Accordingly, in an implementation where the first user device

[102] is connected to a 5G network, the processing unit

[202] can select a low generation radio access technology (RAT) at the first user device

[102] , such as 4G.

[0040] Further, in an implementation, to select the low generation RAT, the processing unit

[202] is configured to send an indication to a radio resource control (RRC) layer for selection of the low generation RAT. As generally known in the art, in a 4G network, the RRC layer controls communication between the user device and the base station. The RRC layer is the highest layer in the control plane of the access stratum (AS). Further, the RRC layer also facilitates transfer of messages of a non-access stratum (NAS) layer that is above the RRC layer. The NAS messages are used to control communication between the user device and an evolved packet core (EPC) that is a framework for providing voice and data over a 4G long term evolution (LTE) network. Accordingly, the processing unit

[202] also sends an indication to a non-access stratum (NAS) layer for selection of the low generation RAT.

[0041] Further, the processing unit

[202] sends a tracking area update (TAU) request and a radio resource control (RRC) connection request from the first user device

[102] to the network entity

[106] in response to the selection of the low generation RAT, wherein the RRC connection request includes a cause message. The tracking area update (TAU) request is sent by the first user device

[102] to update a tracking area identity (TAI) on a serving cell when the first user device

[102] detects a change to a new tracking area. Further, the RRC connection request is sent for requesting an evolved universal mobile telecommunications service (UMTS) terrestrial radio access network (E-UTRAN) to establish an RRC connection as generally known in the art.

[0042] Further, as mentioned earlier in the disclosure, the RRC connection request includes a cause message. In an implementation, the cause message (i.e., the RRC connection request cause message) includes at least one of the following: cause - mobile originating voice call (cause-MO-voice call) for the first user equipment

[102] and cause - mobile terminated access (cause-MT-access) for the second user equipment

[104] . Here, if the cause of failure is on the mobile originating (MO) side, i.e., on the first user equipment

[102] side, where the first user equipment

[102] is making a voice call to the second user equipment

[104] , the cause-MO-voice call is sent along with the RRC connection request. Further, if the cause of failure is on the mobile terminated (MT) side, i.e., on the second user equipment

[104] side, where the first user equipment

[102] is making a voice call to the second user equipment

[104] , the cause-MT-access is sent along with the RRC connection request. The cause-MO-voice call and the cause-MT-access are initiated for the RRC connection establishment to send a tracking area update. Thus, the processing unit

[202] detects, at the first user equipment

[102] , initiation of a tracking area update (TAU) procedure based on the RRC connection establishment by the cause message.

[0043] Further, the processing unit

[202] detects, at the first user equipment

[102] , establishment of an Internet Protocol Multimedia Subsystem (IMS) and one or more Public Data Network (PDN) default bearers by the network entity

[106] . As generally known in the art, the IMS is a standards-based architectural framework for delivering multimedia communication services such as voice, video and text messaging over Internet Protocol (IP) networks. The IMS network can be a network separate from the normal Internet and can be associated with a separate access point name (APN) of its own. Further, there can be a separate default bearer for the IMS network. Further, as generally known in the art, the user equipment uses a PDN connectivity procedure to request creation of a default evolved packet service bearer (EPS bearer) to a PDN. Here, the user equipment requests connectivity to a PDN by sending a PDN connectivity request (PDN CONNECTIVITY REQUEST) message to the network. If the request is accepted by the network, it initiates establishment of a default EPS bearer context activation procedure. This procedure is used to establish a default bearer, here referred to as a PDN default bearer. Further, in case the IMS and the PDN default bearer are established, the TAU request is considered successful.

[0044] Further, when the TAU procedure is used for "MO-voice call" or "MT-access", the network entity

[106] sends an "activate dedicated bearer request" for the voice call to the user equipment. Accordingly, the processing unit

[202] receives, at the first user equipment

[102] , the "activate dedicated bearer request" for the voice call from the network entity

[106] based on the IMS and one or more PDN default bearers. The dedicated bearer provides a dedicated path for one or more specific services such as the voice call. The dedicated bearer acts as an additional bearer on top of the default bearer.

[0045] Further, the processing unit

[202] detects, for the first user equipment

[102] , a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request. Finally, the processing unit

[202] establishes the voice call between the first user equipment

[102] and the second user equipment

[104] based on the dedicated bearer to start the real-time transport control protocol (RTCP) / real-time transport protocol (RTP) stream. Relatedly, in the context of this procedure, the 6 seconds retry timer of the telecommunication application server (TAS) (wherein the retry is done every 2 seconds for non-invited SIP messages as per the RFC standard 3261) is running, within which the dedicated bearer for establishing the voice call is established. Accordingly, the establishment of the voice call using the procedure as disclosed above does not take extra time and, thus, the RFC standard is not violated when establishing the voice call with the procedure explained above.

[0046] Reference is now made to Figure 3 which shows an exemplary method flowchart

[300] for establishing a voice call between a first user equipment

[102] and a second user equipment

[104] according to an embodiment of the present disclosure. The method starts at step 302 and proceeds to step 304 when a counter-timer expires after no packet data unit (PDU) modification bearer (e.g., 5QI=1 / PDU modification bearer) is received from the network in case of VoNR or no RRC release with redirection (RWR) command is received from the network in case of EPSFB. At step 304, the method includes detecting, by the processing unit

[202] at the first user equipment

[102] , initiation of a voice call procedure for establishing a voice call between the first user equipment

[102] and the second user equipment

[104] via the network entity

[106] . The voice call procedure is for handling call failure, i.e., for avoiding call failure. The voice call procedure can be implemented specifically to avoid call failure in case of network failure for RRC release with redirection (RWR) or 5QI=1 (i.e., 5G quality of service identifier = 1) packet data unit (PDU) modification failure.

[0047] In an implementation, the processing unit

[202] initiates an invitation message for the voice call, at the first user equipment

[102] , prior to detecting, at the first user equipment

[102] , initiation of a voice call procedure for establishing a voice call between the first user equipment

[102] and the second user equipment

[104] via the network entity

[106] . For example, to initiate an invitation message for a mobile originating (MO) / mobile terminating (MT) voice call, the user equipment (UE) initiates an invite (INVITE) message with a private-access network information (P-ANI) header of "3GPP-NR-FDD / TDD" and session description protocol (SDP) content with an enhanced voice service (EVS) audio codec. With this initiation, the network entity

[106] sends a "183 session in progress" message to the user equipment. In other words, the processing unit

[202] receives, at the first user equipment

[102] , a session-in-progress message from the network entity

[106] . As is generally known in the art, the "183 session in progress" message provides a header and media that can be used to convey information about the voice call.

[0048] Further, the processing unit

[202] starts a counter-timer at the first user equipment

[102] for a predefined time period. The counter-timer is started for receiving one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period. In a preferred implementation, the predefined time period is 3000 milliseconds (ms). In other implementations, the predefined time can be in the range of 2000 ms to 3500 ms. Additionally, in an implementation, the counter-timer is started at the IMS layer of the first user equipment

[102] .

[0049] Further, the processing unit

[202] detects, at the first user equipment

[102] , an indication of one of successful reception and unsuccessful reception of one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period. In case of VoNR, a PDU modify bearer (such as 5 QI=1 / PDU modify bearer) is expected to be received from the network, and in case of EPSFB, a RRC release with redirection (RWR) is expected to be received from the network. Here, in case the processing unit

[202] detects an indication of successful reception of one of a packet data unit (PDU) modify bearer in case of VoNR and an indication of successful reception of a RRC release with redirection (RWR) command in case of EPS fallback within the predefined time period, the voice call can be established between the first user equipment

[102] and the second user equipment

[104] via the network entity

[106] by following the standard procedure.

[0050] In an implementation, in case the processing unit

[202] detects an indication of non-successful reception of one of a packet data unit (PDU) modify bearer and a radio resource control (RRC) release with redirection (RWR) command within a predefined time period, the processing unit

[202] initiates a voice call procedure based on the non-successful reception. In an example, the PDU modify bearer (e.g., 5QI=1 / PDU modify bearer) or the RWR can not be received by the first user device

[102] due to network failure or any other reason. Further, the voice call procedure is a procedure that enables to avoid voice call failure and establish a voice call even when the first user device

[102] does not receive the 5QI=1 / PDU modify bearer or the RWR command within a predefined time period, like for example 3000 ms, after which a counter-timer expires.

[0051] Thus, after the counter-timer expires without receiving the 5QI=1 / PDU modify bearer or the RWR command, the processing unit

[202] detects initiation of a voice call procedure for establishing a voice call between the first user device

[102] and the second user device

[104] via the network entity

[106] , as shown in step 304 in Figure 3

[0052] After detecting the initiation of the voice call procedure, at step 306, the method includes selecting, by the processing unit

[202] at the first user device

[102] , a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure. The low generation RAT can be any previous generation of mobile communication compared to the latest generation RAT through which the first user device

[102] is connected to the network entity

[106] . For example, the first user device

[102] is connected to the network entity

[106] through a 5G (i.e., fifth generation) network. Thus, the low generation RAT can be 4G, 3G, and 2G (i.e., fourth, third, and second generation mobile communications, which are generally known in the art). Thus, in the implementation where the first user device

[102] is connected to a 5G network, the processing unit

[202] at the first user device

[102] can select a low generation radio access technology (RAT), like 4G.

[0053] ​Additionally, in an implementation, to select the lower generation RAT, the processing unit

[202] sends an indication to a radio resource control (RRC) layer for selection of the lower generation RAT. As generally known in the art, in a 4G network, the RRC layer controls communication between the user equipment and the base station. The RRC layer is the highest layer in the control plane of the access stratum (AS). Further, the RRC layer also facilitates transfer of messages of a non-access stratum (NAS) layer that is above the RRC layer. The NAS messages are used to control communication between the user equipment and an evolved packet core (EPC), which is a framework for providing voice and data over 4G long term evolution (LTE) networks. Accordingly, the processing unit

[202] also sends an indication to a non-access stratum (NAS) layer for selection of the lower generation RAT.

[0054] Further, at step 308, the method includes sending, by the processing unit

[202] , a tracking area update request and a radio resource control (RRC) connection request from the first user equipment

[102] to the network entity

[106] in response to the selection of the lower generation RAT, wherein the RRC connection request includes a cause message. The tracking area update (TAU) request is sent by the first user equipment

[102] when the first user equipment

[102] detects a change to a new tracking area to update a tracking area identity (TAI) on a serving cell. Additionally, as generally known in the art, the RRC connection request is sent for requesting an evolved universal mobile telecommunications service (UMTS) terrestrial radio access network (E-UTRAN) to establish an RRC connection.

[0055] Further, as mentioned earlier in the disclosure, the RRC connection request includes a cause message. In an implementation, the cause message (i.e., the RRC connection request cause message) includes at least one of the following: cause - mobile originating voice call (cause-MO-voice call) for the first user equipment

[102] and cause - mobile terminated access (cause-MT-access) for the second user equipment

[104] . Here, if the cause of the failure is on the mobile originating (MO) side, i.e., on the first user equipment

[102] side, where the first user equipment

[102] is making a voice call to the second user equipment

[104] , the cause-MO-voice call is sent along with the RRC connection request. Further, if the cause of the failure is on the mobile terminated (MT) side, i.e., on the second user equipment

[104] side, where the first user equipment

[102] is making a voice call to the second user equipment

[104] , the cause-MT-access is sent along with the RRC connection request. The cause-MO-voice call and the cause-MT-access are initiated for the RRC connection establishment to send the tracking area update. Thus, at step 310, the method includes detecting, by the processing unit

[102] at the first user equipment

[102] , initiation of a tracking area update procedure based on the RRC connection establishment by the cause message.

[0056] Further, at step 312, the method includes detecting, by the processing unit

[102] at the first user equipment

[102] , establishment of an Internet Protocol Multimedia Subsystem (IMS) and one or more Public Data Network (PDN) default bearers by the network entity

[106] . As generally known in the art, the IMS is a standards-based architectural framework for delivering multimedia communication services such as voice, video and text messaging over Internet Protocol (IP) networks. The IMS network can be a network separate from the normal Internet and can be associated with a separate access point name (APN) of its own. Further, there can be a separate default bearer for the IMS network. Further, as generally known in the art, the user equipment uses a PDN connectivity procedure to request creation of a default evolved packet service bearer (EPS bearer) to a PDN. Here, the user equipment requests connectivity to a PDN by sending a PDN connectivity request (PDN CONNECTIVITY REQUEST) message to the network. If the request is accepted by the network, it initiates establishment of a default EPS bearer context activation procedure. This procedure is used to establish a default bearer, here referred to as the PDN default bearer. Further, with the IMS and the PDN default bearer established, the TAU request is considered successful.

[0057] Further, when the TAU procedure is for "MO-voice call" or "MT-access", the network entity

[106] sends an "activate dedicated bearer request" for the voice call to the user equipment. Thus, at step 314, the method includes receiving, by the processing unit

[102] , at the first user equipment

[102] , the activate dedicated bearer request for the voice call from the network entity

[106] based on the IMS and the one or more PDN default bearers. The dedicated bearer provides a dedicated path for one or more specific services such as the voice call. The dedicated bearer acts as an additional bearer on top of the default bearer.

[0058] Further, at step 316, the method includes detecting, by the processing unit

[102] , the dedicated bearer for the first user equipment

[102] , wherein the dedicated bearer is created based on the activate dedicated bearer request. Finally, at step 318, the method includes establishing, by the processing unit

[102] , the voice call between the first user equipment

[102] and the second user equipment

[104] based on the dedicated bearer to start the real-time transport control protocol (RTCP) / real-time transport protocol (RTP) stream, and the method terminates at step 320 upon establishing the voice call. Relatedly, in the context of this procedure, the 6 seconds retry timer of the telecommunication application server (TAS) (wherein the retry is done every 2 seconds for non-invited SIP messages as per the RFC standard 3261) is running within which the dedicated bearer for creating the voice call is established. Thus, the establishing of the voice call using the procedure as disclosed above does not take extra time and hence, the RFC standard is not violated upon establishing the voice call with the procedure explained above.

[0059] Reference is now made to Figure 4 which shows a detailed exemplary flow chart of the method for establishing the voice call between the first user equipment

[102] and the second user equipment

[104] according to the exemplary embodiment of the present disclosure. It is suitably mentioned that, Figure 4 The flow chart shown is exemplary only and is provided for understanding purposes, and Figure 4The illustrated flowchart does not limit or restrict the disclosure in any way. In this example case, the first user equipment

[102] makes a voice call to the second user equipment

[104] via the network entity

[106] . As illustrated, at step 402, the user initiates the voice call while the first user equipment

[102] is connected to the network entity

[106] via a 5G network. At step 404, the first user equipment

[102] sends a mobile originated (MO) session initiation protocol (SIP) invite to the network entity

[106] . At step 406, the telecommunication application server (TAS) responds to the sent SIP invite. Here, the TAS receives a response for the MO SIP invite from a mobile terminated (MT) user equipment (i.e., the second user equipment

[104] ) and then responds to the MO user equipment (i.e., the first user equipment

[102] ). Additionally, as illustrated at step 408, if the TAS does not respond to the SIP invite, a 14 second timer with three retries at 2 second, 4 second, 8 second intervals for the SIP invite is started at the first user equipment

[102] . The 14 second timer is set in accordance with a relevant request for comments (RFC) standard. If the TAS responds to the SIP invite for the first user equipment

[102] , a “100 trying” response procedure is initiated as illustrated at step 410. Further, if the first user equipment

[102] does not receive the “100 trying” response at step 410, a 6 second timer with three retries at 2 second intervals is started at the first user equipment

[102] in accordance with the RFC standard as illustrated in step 412. If the first user equipment

[102] receives the “100 trying” response at step 410, an indication related to “183-session-in-progress” is received at the first user equipment

[102] as illustrated in step 414. Further, if the indication related to “183-session-in-progress” received at the first user equipment

[102] at step 414 indicates that the “183-session-in-progress” has not started, then a 6 second timer with three retries at 2 second intervals is started at the first user equipment

[102] in accordance with the RFC standard as illustrated in step 412. If the indication related to “183-session-in-progress” received at the first user equipment

[102] at step 414 indicates that the “183-session-in-progress” has started, then a 3 second timer is triggered at the first user equipment IP multimedia subsystem (IMS) stack as illustrated at step 416. Further, at step 418, it is checked whether the RWR command or 5QI=1 PDU modification is received within 3 seconds on the MO side and / or the MT side.If the RWR command or 5QI=1 PDU modification is received within 3 seconds, then the call creation is completed with acknowledgement (ACK) as shown in step 420 according to the currently existing procedure and the call is ended / terminated as shown in step 436. Further, if the RWR command or 5QI=1 PDU modification is not received within 3 seconds, then at step 422 the first user equipment

[102] reselects a radio access technology (RAT), i.e. a low RAT, such as 4G (or LTE). At steps 424 and 426, the first user equipment

[102] sends a tracking area unit (TAU) request with IMS and data bearers and a radio resource control (RRC) connection request, wherein the RRC connection request includes a cause message. The cause message includes at least one of the following: cause - mobile originating voice call (cause-MO-voice call) for the first user equipment

[102] and cause - mobile terminated access (cause-MT-access) for the second user equipment

[104] . In an implementation, steps 424 and 426 occur simultaneously with or without a small time delay. If the TAU request is accepted by the network entity

[106] as shown in step 428, it initiates the establishment of a default EPS bearer context activation procedure. This procedure is used to establish a default bearer, here referred to as a PDN default bearer. In addition, the TAU request is considered successful if the IMS and PDN default bearer are established. Further, the SIP signaling is resumed as shown in step 430 and the dedicated bearer is established as shown in step 432. In addition, the call creation is completed with acknowledgement (ACK) as shown in step 434. Thereby, the call setup procedure is completed and the call is ended / terminated as shown in step 436, i.e. the call is ended with an IMS SIP BYE because of "user disconnection".

[0060] Further, aspects of the disclosure can be directed to a first user equipment for establishing a voice call. The first user equipment includes a system. The system further includes a processing unit. The processing unit is configured to detect, at the first user equipment, an initiation of a voice call procedure for establishing a voice call between the first user equipment and a second user equipment via a network entity. Further, the processing unit is configured to select, at the first user equipment, a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure. Moreover, the processing unit is configured to send, from the first user equipment to the network entity, a tracking area update request and a radio resource control (RRC) connection request in response to the selection of the low generation RAT, wherein the RRC connection request includes a cause message. Further, the processing unit is configured to detect, at the first user equipment, an initiation of a tracking area update procedure based on the RRC connection establishment by the cause message. The processing unit is further configured to detect, at the first user equipment, an establishment of an internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity. Moreover, the processing unit is configured to receive, at the first user equipment from the network entity, an activate dedicated bearer request for the voice call based on the IMS and the one or more PDN default bearers. Further, the processing unit is configured to detect, for the first user equipment, a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request. Moreover, the processing unit is configured to establish the voice call between the first user equipment and the second user equipment based on the dedicated bearer to start the RTCP / RTP flow.

[0061] Thus, the present invention provides a novel solution for establishing a voice call between a first user equipment and a second user equipment. The present invention provides a solution that is technically superior to the currently known solutions as it is able to create a voice call in case of network failure for RRC release with redirection (RWR) or 5QI=1 (i.e. 5G quality of service identifier = 1) packet data unit (PDU) modification failure. Further, implementation of features as explained in the present disclosure will enable a person skilled in the art to reduce voice call failures on user equipment, thereby improving key performance indicators (KPIs) of network providers and optimizing faster registration of user equipment to the network. Implementation of features of the present invention also improves battery efficiency of the user equipment. Further, implementation of features as disclosed above will enable one to obtain a mechanism to maintain a call even in case of network failure on advanced RAT by giving control to the user equipment to reselect a low RAT.

[0062] While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many modifications are possible in the preferred embodiments, and many changes can be made in the preferred embodiments without departing from the principles of the application. These and other changes in the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, which demonstrates the preferred embodiments of the application and teaches how to make and use them. Accordingly, the foregoing description is intended to be illustrative only rather than limiting of the application, as broadly defined by the following claims.

Claims

1. A method for establishing a voice call, the method comprising: - detecting, by a processing unit [202], at a first user equipment [102], initiation of a voice call procedure for establishing the voice call between the first user equipment [102] and a second user equipment [104] via a network entity [106]; - selecting, by the processing unit [202], at the first user equipment [102], a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure; - sending, by the processing unit [202], from the first user equipment [102] to the network entity [106], in response to the selection of the low generation RAT, a tracking area update request and a radio resource control (RRC) connection request, wherein the RRC connection request comprises a cause message; - detecting, by the processing unit [102], at the first user equipment [102], initiation of a tracking area update procedure based on RRC connection establishment by the cause message; - detecting, by the processing unit [102], at the first user equipment [102], establishment of an internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity [106]; - receiving, by the processing unit [102], at the first user equipment [102], an activate dedicated bearer request for the voice call from the network entity [106] based on the IMS and the one or more PDN default bearers; - detecting, by the processing unit [102], for the first user equipment [102], a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request; and - establishing, by the processing unit [102], the voice call between the first user equipment [102] and the second user equipment [104] based on the dedicated bearer.

2. The method of claim 1, wherein, the cause message comprises at least one of: a cause - mobile originating - voice call (cause-MO-voice call) for the first user equipment [102] and a cause - mobile terminating - access (cause-MT-access) for the second user equipment [104].

3. The method of claim 1, wherein, selecting, by the processing unit [202], at the first user equipment [102], the low generation RAT further comprises: - sending, by the processing unit [202], an indication to a RRC layer for selecting the low generation RAT; and - sending, by the processing unit [202], an indication to a non-access stratum (NAS) layer for selecting the low generation RAT.

4. The method of claim 1, wherein, prior to detecting, by the processing unit [202], at the first user equipment [102], the initiation of the voice call procedure for establishing the voice call between the first user equipment [102] and the second user equipment [104] via the network entity [106], the method comprises: - initiating, by the processing unit [202], at the first user equipment [102], an invite message for the voice call; - receiving, by the processing unit [202], at the first user equipment [102], a session-in-progress message from the network entity [106]; - starting, by the processing unit [202], at the first user equipment [102], a counter-timer for a predefined time period, wherein the counter-timer is started for receiving one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period; - detecting, by the processing unit [202], at the first user equipment [102], an indication of unsuccessful reception of one of the packet data unit (PDU) modify bearer and the RRC release with redirection (RWR) command within the predefined time period; and - initiating, by the processing unit [202], at the first user equipment [102], the voice call procedure based on the unsuccessful reception.

5. The method of claim 4, wherein, The predefined time period is in a range of 2000 milliseconds to 3500 milliseconds.

6. The method of claim 4, wherein, The counter-timer is started on an IMS layer of the first user equipment [102].

7. A system for establishing a voice call, the system comprising: - a processing unit [202] configured to: detect, at a first user equipment [102], initiation of a voice call procedure for establishing the voice call between the first user equipment [102] and a second user equipment [104] via a network entity [106]; select, at the first user equipment [102], a low generation radio access technology (RAT) based on detection of the initiation of the voice call procedure; send, from the first user equipment [102] to the network entity [106], a tracking area update request and a radio resource control (RRC) connection request in response to selection of the low generation RAT, wherein the RRC connection request includes a cause message; detect, at the first user equipment [102], initiation of a tracking area update procedure based on RRC connection setup by the cause message; detect, at the first user equipment [102], establishment of internet protocol multimedia subsystem (IMS) and one or more public data network (PDN) default bearers by the network entity [106]; receive, at the first user equipment [102], an activate dedicated bearer request for the voice call from the network entity [106] based on the IMS and the one or more PDN default bearers; detect, for the first user equipment [102], a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request; and establish, between the first user equipment [102] and the second user equipment [104], the voice call based on the dedicated bearer.

8. The system of claim 7, wherein, The cause message comprises at least one of a cause - mobile originating voice call (cause-MO-voice call) for the first user equipment [102] and a cause - mobile terminated access (cause-MT-access) for the second user equipment [104].

9. The system of claim 7, wherein, To select the low generation RAT, the processing unit [202] is further configured to: - send an indication to a RRC layer for selecting the low generation RAT; and - send an indication to a non-access stratum (NAS) layer for selecting the low generation RAT.

10. The system of claim 7, wherein, Before detecting initiation of the voice call procedure for establishing the voice call between the first user equipment [102] and the second user equipment [104] via the network entity [106], the processing unit [202] is configured to: - initiate, at the first user equipment [102], an invite message for the voice call; - receive, at the first user equipment [102], a session-in-progress message from the network entity [106]; - start, at the first user equipment [102], a counter-timer for a predefined time period, wherein the counter-timer is started for receiving one of a packet data unit (PDU) modify bearer and a RRC release with redirection (RWR) command within the predefined time period; - detect, at the first user equipment [102], an indication of unsuccessful reception of one of the packet data unit (PDU) modify bearer and the RRC release with redirection (RWR) command within the predefined time period; and - initiate, at the first user equipment [102], the voice call procedure based on the unsuccessful reception.

11. The system of claim 10, wherein, The predefined time period is in a range of 2000 milliseconds to 3500 milliseconds.

12. The system of claim 10, wherein, The counter-timer is started on an IMS layer of the first user equipment [102].

13. A first user equipment for establishing a voice call, the first user equipment comprising: - a system, wherein the system comprises a processing unit [202] configured to: detect, at the first user equipment [102], initiation of a voice call procedure for establishing the voice call between the first user equipment [102] and a second user equipment [104] via a network entity [106]; select, at the first user equipment [102], a low generation radio access technology (RAT) based on the detection of the initiation of the voice call procedure; send, from the first user equipment [102] to the network entity [106], a tracking area update request and a radio resource control (RRC) connection request in response to the selection of the low generation RAT, wherein the RRC connection request comprises a cause message; detect, at the first user equipment [102], initiation of a tracking area update procedure based on RRC connection setup by the cause message; and - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises: - a memory [204] coupled to the processing unit [202].

13. The first user equipment of claim 12, wherein the system further comprises detecting, at the first user equipment [102], establishment of an Internet Protocol Multimedia Subsystem (IMS) and one or more Public Data Network (PDN) default bearers by the network entity [106]; receiving, at the first user equipment [102], an activate dedicated bearer request for the voice call from the network entity [106] based on the IMS and the one or more PDN default bearers; detecting, for the first user equipment [102], a dedicated bearer, wherein the dedicated bearer is created based on the activate dedicated bearer request; and establishing the voice call between the first user equipment [102] and the second user equipment [104] based on the dedicated bearer.

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