FORM 2
THE PATENTS ACT, 1970 (39 OF 1970) & THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“METHOD AND SYSTEM FOR TRANSMITTING A SESSION INITIATION PROTOCOL ERROR RESPONSE TO A TARGET
NETWORK-NODE”
We, Jio Platforms Limited, an Indian National, of Office - 101, Saffron, Nr. Centre Point, Panchwati 5 Rasta, Ambawadi, Ahmedabad - 380006, Gujarat, India.
The following specification particularly describes the invention and the manner in which it is to be performed.

METHOD AND SYSTEM FOR TRANSMITTING A SESSION INITIATION PROTOCOL ERROR RESPONSE TO A TARGET NETWORK-NODE
TECHNICAL FIELD
[0001] Embodiments of the present disclosure generally relate to network management systems. More particularly, embodiments of the present disclosure relate to methods and systems for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network.
BACKGROUND
[0002] The following description of the related art is intended to provide background information pertaining to the field of the disclosure. This section may include certain aspects of the art that may be related to various features of the present disclosure. However, it should be appreciated that this section is used only to enhance the understanding of the reader with respect to the present disclosure, and not as admissions of the prior art.
[0003] Wireless communication technology has rapidly evolved over the past few decades, with each generation bringing significant improvements and advancements. The first generation of wireless communication technology was based on analog technology and offered only voice services. However, with the advent of the second-generation (2G) technology, digital communication and data services became possible, and text messaging was introduced. The third generation (3G) technology marked the introduction of high-speed internet access, mobile video calling, and location-based services. The fourth generation (4G) technology revolutionized wireless communication with faster data speeds, better network coverage, and improved security. Currently, the fifth generation (5G) technology is being deployed, promising even faster data speeds, low latency, and the ability to connect multiple devices simultaneously. With each generation, wireless communication technology has become more advanced, sophisticated, and capable of delivering more services to its users.
[0004] In the field of telecommunication, an offnet call refers to telephone call made between users who are connected to different telecommunications networks or operators. For example, if the user uses one mobile network such as network A and calls someone who uses a different mobile network such as network B, that call is considered an offnet call. The offnet call typically involve routing through various network elements and interfaces to connect the caller to the recipient, often involving interconnection agreements between different operators to facilitate seamless communication across networks.

[0005] Further, the present solutions have several shortcomings such as inability to effectively manage offnet calls in telecommunications networks, particularly inaccurately diagnosing and addressing call failures associated with the offnet calls. The current setup, characterized by uniform SIP error code dispatch for all ISUP failures, such setup hampers specific issue identification and resolution. This limitation prolongs downtime, diminishes network performance, and underscores the need for enhanced error code differentiation and diagnostic capabilities.
[0006] Firstly, offnet calls originate from the Breakout Gateway Control Function (BGCF) and are directed to the Media Gateway Control Function (MGCF) via a Mj interface, which typically uses the Session Initiation Protocol (SIP) for communication. From there, the MGCF routes the call to the intended recipient's operator over the ISUP (Integrated Services Digital Network User Part) interface. The Mj interface refers to a specific interface used in telecommunications networks, particularly in the context of the IP Multimedia Subsystem (IMS) architecture. The Mj interface is responsible for facilitating communication between the Breakout Gateway Control Function (BGCF) and the Media Gateway Control Function (MGCF).
[0007] However, if something goes wrong during this process and the offnet call encounters a failure while trying to connect via the ISUP interface, the MGCF takes action by rejecting the call back at the Mj interface, using a specific SIP error code like a 480 response to indicate the failure. The ISUP interface, also known as the ISDN User Part interface, is a key component in telecommunications networks, particularly in the context of circuit-switched networks like the Public Switched Telephone Network (PSTN). ISUP facilitates the signalling necessary for the setup, maintenance, and teardown of voice calls between different network switches.
[0008] Hence, the current telecommunication architectures are unable to effectively manage offnet calls in telecommunications networks, particularly in accurately diagnosing and addressing call failures. The current available setup, characterized by uniform SIP error code dispatch for all ISUP failures, hampers specific issue identification and resolution. This limitation prolongs downtime, diminishes network performance.
[0009] Therefore, there is a need to provide a method and system for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network.
SUMMARY

[0010] This section is provided to introduce certain aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.
[0011] An aspect of the present disclosure may relate to a method for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network. The method comprises receiving, by a transceiver unit via an interface, a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses. The method comprises mapping, by a processing unit at a Breakout Gateway Control Function (BGCF) node in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes. The method comprises detecting, by the processing unit at a Media Gateway Control Function (MGCF) node in the network, a rejected call from a user equipment in the network. The method comprises identifying, by the processing unit, a rejected call cause code associated with the rejected call. The method comprises determining, by the processing unit, a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status. The method comprises identifying, by the processing unit, a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status. The method comprises generating, by the processing unit at the BGCF node in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code. The method comprises transmitting, by the transceiver unit from the BGCF node to the target node in the network, the SIP error response based on the generating the SIP error response.
[0012] In an exemplary aspect of the present disclosure, the positive cause code status is determined in an event the rejected call cause code is a successful match with at least one of the ISUP cause code from the list of ISUP cause codes, and wherein the negative cause code status is determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes from the list of ISUP cause codes.
[0013] In an exemplary aspect of the present disclosure, the method further comprises transmitting, by the transceiver unit from the BGCF node, the rejected call SIP error response, in an event the negative cause code status is detected.

[0014] In an exemplary aspect of the present disclosure, the generating the SIP error response associated with the target ISUP cause code based on the identifying the SIP error code associated with the target ISUP cause code further comprises changing, by the processing unit, the rejected call SIP error response to the SIP error response associated with the target ISUP cause code.
[0015] In an exemplary aspect of the present disclosure, the identifying the rejected call cause code associated with the rejected call from the user equipment in the network further comprises determining, by the processing unit, an available rejected cause code status, wherein the available rejected cause code status is determined based on receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
[0016] In an exemplary aspect of the present disclosure, the rejected call SIP error response is transmitted by the transceiver unit from the BGCF node, in an event of determining an unsuccessful receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
[0017] Another aspect of the present disclosure may relate to a system for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network. The system comprises a transceiver unit, wherein the transceiver unit is configured to receive, via an interface, a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses. The system comprises a processing unit connected to at least the transceiver unit, wherein the processing unit configured to map, at a Breakout Gateway Control Function (BGCF) node in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes. The processing configured to detect, at a Media Gateway Control Function (MGCF) node in the network, a rejected call from a user equipment in the network. The processing unit further configured to identify; a rejected call cause code associated with the rejected call. The processing unit further configured to determine, a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status. The processing unit further configured to identify, a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status. The processing unit further configured to generate, at the BGCF node in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code. The transceiver unit is further configured to transmit, from the BGCF node to the target node in the network, the SIP error response based on the generated SIP error response.

[0018] Another aspect of the present disclosure may relate to a User Equipment (UE) for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, the UE comprising a memory, and a processor coupled to the memory. Further, the processor is configured to transmit, to a system via an interface, at least one of: a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses, and receive, from the system, an SIP error response based on at least one of the list of ISUP cause codes, a list of SIP error codes and a list of SIP error responses. Further, the SIP error response is received based on mapping, by the system at a Breakout Gateway Control Function (BGCF) node in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes. Further, the SIP error response is received based on detecting, by the system at a Media Gateway Control Function (MGCF) node in the network, a rejected call from a user equipment in the network. Further, the SIP error response is received based on identifying, by the system, a rejected call cause code associated with the rejected call. Further, the SIP error response is received based on determining, by the system, a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status. Further, the SIP error response is received based on identifying, by the system, a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status. Further, the SIP error response is received based on generating, by the system at the BGCF node in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code. Thereafter, the SIP error response is received based on transmitting, by the system from the BGCF node to the target node in the network, the SIP error response based on the generating the SIP error response.
[0019] Yet another aspect of the present disclosure may relate to a non-transitory computer readable storage medium storing instructions for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network the instructions include executable code which, when executed by one or more units of a system, causes a transceiver unit of the system to receive, via an interface, a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses. The instructions further include executable code, which when executed causes a processing unit of the system to map, at a Breakout Gateway Control Function (BGCF) node in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP

cause code is mapped with at least the SIP error response associated with the one or more SIP error
codes. The instructions further include executable code, which when executed causes the processing
unit: to detect, at a Media Gateway Control Function (MGCF) node in the network, a rejected call from
a user equipment in the network; to identify, a rejected call cause code associated with the rejected call,
5 wherein the rejected call cause code comprises a rejected call SIP error response; to determine, a cause
code status associated with the rejected call cause code based on matching the rejected call cause code
and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status
and a negative cause code status; to identify, a target ISUP cause code from the list of ISUP cause codes
based on the positive cause code status; and to generate, at the BGCF node in the network, the SIP error
10 response associated with the target ISUP cause code based on identifying the SIP error code associated
with the target ISUP cause code. The instructions further include executable code, which when executed causes the transceiver unit to transmit, from the BGCF node to the target node in the network, the SIP error response based on the generated SIP error response.
15 OBJECTS OF THE INVENTION
[0020] Some of the objects of the present disclosure, which at least one embodiment disclosed herein satisfies are listed herein below.
20 [0021] It is an object of the present disclosure to provide a system and a method for transmitting a
Session Initiation Protocol (SIP) error response to a target node in a network.
[0022] It is another object of the present disclosure to provide a solution that delivers one or more appropriate announcements to an end user based on an exact reason of call failure. 25
[0023] It is another object of the present disclosure to provide a solution that delivers accurate Key Performance Indicators (KPIs) of the network, enabling operators to obtain real-time information about their network performance.
30 [0024] It is another object of the present disclosure to provide a solution that give flexibility to the
operator for defining the required session initiation protocol error response code in their network.
DESCRIPTION OF THE DRAWINGS
35
[0025] The accompanying drawings, which are incorporated herein, and constitute a part of this disclosure, illustrate exemplary embodiments of the disclosed methods and systems in which like
7

reference numerals refer to the same parts throughout the different drawings. Components in the
drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the
principles of the present disclosure. Also, the embodiments shown in the figures are not to be construed
as limiting the disclosure, but the possible variants of the method and system according to the disclosure
5 are illustrated herein to highlight the advantages of the disclosure. It will be appreciated by those skilled
in the art that disclosure of such drawings includes disclosure of electrical components or circuitry commonly used to implement such components.
[0026] FIG. 1 illustrates an exemplary block diagram representation of 5th generation core (5GC)
10 network architecture.
[0027] FIG. 2 illustrates an exemplary block diagram of a computing device upon which the features of the present disclosure may be implemented in accordance with exemplary implementation of the present disclosure. 15
[0028] FIG. 3 illustrates an exemplary block diagram of a system for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, in accordance with exemplary implementations of the present disclosure.
20 [0029] FIG. 4 illustrates a method flow diagram for transmitting a Session Initiation Protocol (SIP)
error response to a target node in a network, in accordance with exemplary implementations of the present disclosure.
[0030] FIG. 5 illustrates an exemplary network environment diagram for transmitting a Session
25 Initiation Protocol (SIP) error response to a target node in a network, in accordance with exemplary
implementations of the present disclosure.
[0031] FIG. 6 illustrates an exemplary method flow diagram for transmitting a Session Initiation
Protocol (SIP) error response to a target node in a network, in accordance with exemplary
30 implementations of the present disclosure.
[0032] The foregoing shall be more apparent from the following more detailed description of the disclosure.
35 DETAILED DESCRIPTION
8

[0033] In the following description, for the purposes of explanation, various 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 may be practiced without these specific
details. Several features described hereafter may each be used independently of one another or with any
5 combination of other features. An individual feature may not address any of the problems discussed
above or might address only some of the problems discussed above.
[0034] 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
10 embodiments will provide those skilled in the art with an enabling description for implementing an
exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the disclosure as set forth.
[0035] Specific details are given in the following description to provide a thorough understanding of
15 the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments
may be practiced without these specific details. For example, circuits, systems, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail.
20 [0036] Also, it is noted that individual embodiments may 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 may describe the operations as a sequential process, many of the operations may be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed but could have additional steps not included in
25 a figure.
[0037] The word “exemplary” and/or “demonstrative” is 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
30 “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 intended to be inclusive—in a manner similar to the term “comprising” as an open transition word—without
35 precluding any additional or other elements.
9

[0038] As used herein, a “processing unit” or “processor” or “operating processor” includes one or
more processors, wherein processor refers to any logic circuitry for processing instructions. A processor
may 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
5 (Digital Signal Processing) DSP core, a controller, a microcontroller, Application Specific Integrated
Circuits, Field Programmable Gate Array circuits, any other type of integrated circuits, etc. The processor may perform signal coding data processing, input/output processing, and/or any other functionality that enables the working of the system according to the present disclosure. More specifically, the processor or processing unit is a hardware processor.
10
[0039] As used herein, “a user equipment”, “a user device”, “a smart-user-device”, “a smart-device”, “an electronic device”, “a mobile device”, “a handheld device”, “a wireless communication device”, “a mobile communication device”, “a communication device” may be any electrical, electronic and/or computing device or equipment, capable of implementing the features of the present disclosure. The
15 user equipment/device may include, but is not limited to, a mobile phone, smart phone, laptop, a
general-purpose computer, desktop, personal digital assistant, tablet computer, wearable device or any other computing device which is capable of implementing the features of the present disclosure. Also, the user device may contain at least one input means configured to receive an input from at least one of a transceiver unit, a processing unit, a storage unit, a detection unit and any other such unit(s) which are
20 required to implement the features of the present disclosure.
[0040] As used herein, “storage unit” or “memory unit” refers to a machine or computer-readable
medium including any mechanism for storing information in a form readable by a computer or similar
machine. For example, a computer-readable medium includes read-only memory (“ROM”), random
25 access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices
or other types of machine-accessible storage media. The storage unit stores at least the data that may be required by one or more units of the system to perform their respective functions.
[0041] As used herein “interface” or “user interface refers to a shared boundary across which two or
30 more separate components of a system exchange information or data. The interface may also be referred
to a set of rules or protocols that define communication or interaction of one or more modules or one or more units with each other, which also includes the methods, functions, or procedures that may be called.
35 [0042] All modules, units, components used herein, unless explicitly excluded herein, may be software
modules or hardware processors, the processors being a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors,
10

one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASIC), Field Programmable Gate Array circuits (FPGA), any other type of integrated circuits, etc.
5 [0043] As used herein the transceiver unit include at least one receiver and at least one transmitter
configured respectively for receiving and transmitting data, signals, information or a combination thereof between units/components within the system and/or connected with the system.
[0044] As discussed in the background section, offnet calls in telecommunications involve connections
10 between users on different networks, necessitating routing through various elements and interfaces
associated with the network/s. However, existing systems often struggle to effectively manage these calls, particularly in diagnosing and addressing failures associated with the offnet calls. Current setups, characterized by the uniform dispatch of Session Initiation Protocol (SIP) error codes for all Integrated Services Digital Network User Part (ISUP) failures, hinder precise issue identification and resolution,
15 resulting in prolonged downtime and reduced network performance. As, calls originate from a Breakout
Gateway Control Function (BGCF) of the network and are routed to a Media Gateway Control Function (MGCF) of the network via the Mj interface, utilizing a Session Initiation Protocol (SIP). If issues arise during this process, such as failures on the ISUP interface, the MGCF rejects the call, often using the SIP error code like 480. Hence the current known solutions have several shortcomings. The present
20 disclosure aims to overcome the above-mentioned and other existing problems in this field of
technology by providing method and system of transmitting to a target node in a network a Session Initiation Protocol (SIP) error response by receiving one or more lists of ISUP cause codes, SIP error codes, and SIP error responses, thereafter, mapping each ISUP cause code to one or more SIP error codes at a Breakout Gateway Control Function (BGCF) node. Then, detecting a rejected call at the
25 Media Gateway Control Function (MGCF) node. Further, once the rejected call is identified the present
novel solution as disclosed in the present disclosure encompasses identifying the rejected call cause code and an associated SIP error response. Thereafter, determining the cause code status based on matching the rejected call cause code with the list of ISUP cause codes. Then, the solution of the present disclosure identifies the target ISUP cause code if the cause code status is positive and based on that
30 generates the SIP error response associated with the target ISUP cause code at the BGCF node.
Thereafter, the present solution transmits the SIP error response from the BGCF node to the target node in the network in order to effectively manage issues associated with the rejected call particularly associated with an offnet call.
35 [0045] FIG. 1 illustrates an exemplary block diagram representation of 5th generation core (5GC)
network architecture, in accordance with exemplary implementation of the present disclosure. As shown in FIG. 1, the 5GC network architecture [100] includes a user equipment (UE) [102], a radio access
11

network (RAN) [104], an access and mobility management function (AMF) [106], a Session
Management Function (SMF) [108], a Service Communication Proxy (SCP) [110], an Authentication
Server Function (AUSF) [112], a Network Slice Specific Authentication and Authorization Function
(NSSAAF) [114], a Network Slice Selection Function (NSSF) [116], a Network Exposure Function
5 (NEF) [118], a Network Repository Function (NRF) [120], a Policy Control Function (PCF) [122], a
Unified Data Management (UDM) [124], an application function (AF) [126], a User Plane Function (UPF) [128], a data network (DN) [130], wherein all the components are assumed to be connected to each other in a manner as obvious to the person skilled in the art for implementing features of the present disclosure.
10
[0046] Radio Access Network (RAN) [104] is the part of a mobile telecommunications system that connects user equipment (UE) [102] to the core network (CN) and provides access to different types of networks (e.g., 5G network). It consists of radio base stations and the radio access technologies that enable wireless communication.
15
[0047] Access and Mobility Management Function (AMF) [106] is a 5G core network function responsible for managing access and mobility aspects, such as UE registration, connection, and reachability. It also handles mobility management procedures like handovers and paging.
20 [0048] Session Management Function (SMF) [108] is a 5G core network function responsible for
managing session-related aspects, such as establishing, modifying, and releasing sessions. It coordinates with the User Plane Function (UPF) [128] for data forwarding and handles IP address allocation and QoS enforcement.
25 [0049] Service Communication Proxy (SCP) [110] is a network function in the 5G core network that
facilitates communication between other network functions by providing a secure and efficient messaging service. It acts as a mediator for service-based interfaces.
[0050] Authentication Server Function (AUSF) [112] is a network function in the 5G core responsible
30 for authenticating UEs during registration and providing security services. It generates and verifies
authentication vectors and tokens.
[0051] Network Slice Specific Authentication and Authorization Function (NSSAAF) [114] is a
network function that provides authentication and authorization services specific to network slices. It
35 ensures that UEs can access only the slices for which they are authorized.
12

[0052] Network Slice Selection Function (NSSF) [116] is a network function responsible for selecting the appropriate network slice for a UE based on factors such as subscription, requested services, and network policies.
5 [0053] Network Exposure Function (NEF) [118] is a network function that exposes capabilities and
services of the 5G network to external applications, enabling integration with third-party services and applications.
[0054] Network Repository Function (NRF) [120] is a network function that acts as a central repository
10 for information about available network functions and services. It facilitates the discovery and dynamic
registration of network functions.
[0055] Policy Control Function (PCF) [122] is a network function responsible for policy control
decisions, such as QoS, charging, and access control, based on subscriber information and network
15 policies.
[0056] Unified Data Management (UDM) [124] is a network function that centralizes the management of subscriber data, including authentication, authorization, and subscription information.
20 [0057] Application Function (AF) [126] is a network function that represents external applications
interfacing with the 5G core network to access network capabilities and services.
[0058] User Plane Function (UPF) [128] is a network function responsible for handling user data traffic, including packet routing, forwarding, and QoS enforcement. 25
[0059] Data Network (DN) [130] refers to a network that provides data services to user equipment (UE) [102] in a telecommunications system. The data services may include but are not limited to Internet services, private data network related services.
30 [0060] FIG. 2 illustrates an exemplary block diagram of a computing device [200] upon which the
features of the present disclosure may be implemented in accordance with exemplary implementation of the present disclosure. In an implementation, the computing device [200] may also implement a method for message routing management. In another implementation, the computing device [200] itself implements the method for message routing management using one or more units configured within the
35 computing device [200], wherein said one or more units are capable of implementing the features as
disclosed in the present disclosure.
13

[0061] The computing device [200] may include a bus [202] or other communication mechanism for
communicating information, and a hardware processor [204] coupled with bus [202] for processing
information. The hardware processor [204] may be, for example, a general-purpose microprocessor.
The computing device [200] may also include a main memory [206], such as a random-access memory
5 (RAM), or other dynamic storage device, coupled to the bus [202] for storing information and
instructions to be executed by the processor [204]. The main memory [206] also may be used for storing
temporary variables or other intermediate information during execution of the instructions to be
executed by the processor [204]. Such instructions, when stored in non-transitory storage media
accessible to the processor [204], render the computing device [200] into a special-purpose machine
10 that is customized to perform the operations specified in the instructions. The computing device [200]
further includes a read only memory (ROM) [208] or other static storage device coupled to the bus [202] for storing static information and instructions for the processor [204].
[0062] A storage device [210], such as a magnetic disk, optical disk, or solid-state drive is provided
15 and coupled to the bus [202] for storing information and instructions. The computing device [200] may
be coupled via the bus [202] to a display [212], such as a cathode ray tube (CRT), Liquid crystal Display (LCD), Light Emitting Diode (LED) display, Organic LED (OLED) display, etc. for displaying information to a computer user. An input device [214], including alphanumeric and other keys, touch screen input means, etc. may be coupled to the bus [202] for communicating information and command
20 selections to the processor [204]. Another type of user input device may be a cursor controller [216],
such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor [204], and for controlling cursor movement on the display [212]. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allow the device to specify positions in a plane.
25
[0063] The computing device [200] may implement the techniques described herein using customized hard-wired logic, one or more ASICs or FPGAs, firmware and/or program logic which in combination with the computing device [200] causes or programs the computing device [200] to be a special-purpose machine. According to one implementation, the techniques herein are performed by the computing
30 device [200] in response to the processor [204] executing one or more sequences of one or more
instructions contained in the main memory [206]. Such instructions may be read into the main memory [206] from another storage medium, such as the storage device [210]. Execution of the sequences of instructions contained in the main memory [206] causes the processor [204] to perform the process steps described herein. In alternative implementations of the present disclosure, hard-wired circuitry
35 may be used in place of or in combination with software instructions.
14

[0064] The computing device [200] also may include a communication interface [218] coupled to the
bus [202]. The communication interface [218] provides a two-way data communication coupling to a
network link [220] that is connected to a local network [222] and the local network [222] is further
connected to the host [224]. For example, the communication interface [218] may be an integrated
5 services digital network (ISDN) card, cable modem, satellite modem, or a modem to provide a data
communication connection to a corresponding type of telephone line. As another example, the
communication interface [218] may be a local area network (LAN) card to provide a data
communication connection to a compatible LAN. Wireless links may also be implemented. In any such
implementation, the communication interface [218] sends and receives electrical, electromagnetic or
10 optical signals that carry digital data streams representing various types of information.
[0065] The computing device [200] can send messages and receive data, including program code,
through the network(s), the network link [220] and the communication interface [218]. In the Internet
example, a server [230] might transmit a requested code for an application program through the Internet
15 [228], the ISP [226], the local network [222] and the communication interface [218]. The received code
may be executed by the processor [204] as it is received, and/or stored in the storage device [210], or other non-volatile storage for later execution.
[0066] Referring to FIG. 3, an exemplary block diagram of a system [300] for transmitting a Session
20 Initiation Protocol (SIP) error response to a target node in a network, is shown, in accordance with the
exemplary implementations of the present disclosure. The system [300] comprises at least one
transceiver unit [302], at least one processing unit [304] and at least one storage unit [306]. Also, all of
the components/ units of the system [300] are assumed to be connected to each other unless otherwise
indicated below. As shown in the figures all units shown within the system should also be assumed to
25 be connected to each other. Also, in FIG. 3 only a few units are shown, however, the system [300] may
comprise multiple such units or the system [300] may comprise any such numbers of said units, as required to implement the features of the present disclosure. Further, in an implementation, the system [300] may be present in a user device to implement the features of the present disclosure.
30 [0067] The system [300] is configured for transmitting a Session Initiation Protocol (SIP) error
response to a target node in a network, with the help of the interconnection between the components/units of the system [300].
[0068] Further, in accordance with the present disclosure, it is to be acknowledged that the
35 functionality described for the various the components/units can be implemented interchangeably.
While specific embodiments may disclose a particular functionality of these units for clarity, it is
recognized that various configurations and combinations thereof are within the scope of the disclosure.
15

The functionality of specific units as disclosed in the disclosure should not be construed as limiting the scope of the present disclosure. Consequently, alternative arrangements and substitutions of units, provided they achieve the intended functionality described herein, are considered to be encompassed within the scope of the present disclosure. 5
[0069] In order to achieve transmission to a target node in a network a Session Initiation Protocol (SIP)
error response, the transceiver unit [302] is configured to receive, via an interface, a list of Integrated
Services Digital Network User Part (ISUP) cause codes, a list Session Initiation Protocol (SIP) error
codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is
10 associated with one or more SIP error responses from the list of SIP error responses.
[0070] As used herein “SIP” is a signalling protocol used for initiating, maintaining, and terminating real-time communication sessions, such as voice call session and a video call session, in an IP Multimedia Subsystem (IMS).
15
[0071] As used herein “list of ISUP cause codes” are used in telecommunications networks to indicate the reason for call failure or call disconnection. Each cause code represents a specific condition or event that led to the failure or disconnection. Further, list of ISUP cause codes may have one or more of cause codes. Each ISUP cause code from the list of ISUP cause codes may indicate various conditions such
20 as call failure, network congestion, subscriber unavailability, or signalling errors, enabling a network
operator in the telecommunication network to diagnose and troubleshoot the issue. Each ISUP cause code from the list of ISUP cause codes corresponds to a specific scenario or event associated with the call establishment or call disconnection in the telecommunication network.
25 [0072] As used herein “SIP error codes” are numeric codes used in SIP responses to indicate the status
of a request. The SIP error code provides information about whether the request was successful, unsuccessful, or encountered an error. Each SIP error code from the list of SIP error codes indicates a failure or issue encountered during a communication session initiation process and/or a communication session handling process. For instance, common SIP error codes include "404 Not Found," indicates
30 that a requested resource was not found, and "503 Service Unavailable," indicates that a server cannot
process the request at the moment due to overload and/or maintenance.
[0073] A SIP error response is a message sent by a SIP server to a client device such as a user device
in response to a failed SIP request and/or a failed SIP operation within a communication session. Each
35 SIP error response from the list of SIP error responses provides a detailed information about the nature
of the error encountered, helping the user device understand a reason of the failed SIP request and/or the failed SIP operation. Each SIP error code from the list of SIP error codes is associated with the one
16

or more SIP error responses from the list of SIP error responses and may include a Session Initiation
Protocol (SIP) reason header to provide context or suggestions for resolution of the failed SIP request
and/or the failed SIP operation. Examples of SIP error responses include "401 Unauthorized," indicating
that the user device needs authentication to proceed, and "500 Server Internal Error," indicating a
5 problem on the server's end. The SIP reason header is a component of SIP which is used to convey an
additional information such as textual description or code to identification a reason of failure of the call request.
[0074] Further, the processing unit [304] is connected to at least the transceiver unit [302] and the
10 processing unit [304] is configured to map, at a Breakout Gateway Control Function (BGCF) node
[504] in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP
error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated
with the one or more SIP error codes. Further, each ISUP cause code is mapped from the list of ISUP
cause codes for establishing a correlation that further assists in transmission of the error response to the
15 target node.
[0075] As used herein “Breakout Gateway Control Function (BGCF)” is function that acts an interface
between one or more networks such as Public Switched Telephone Network (PSTN) network. The
BGCF manage a routing of one or more calls that originate or terminate within the IP Multimedia
20 Subsystem (IMS) network but need to be routed outside the IMS network. The BGCF serves as a bridge
for ensuring a seamless communication between different types of networks.
[0076] Thereafter, the processing unit [304] is configured to detect, at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network.
25
[0077] As used herein “Media Gateway Control Function (MGCF)” refers to a function that serves as an interface between circuit-switched and packet-switched networks, facilitating seamless communication between these distinct network domains. The MGCF is responsible for controlling media gateways (MGWs), which perform the conversion of signalling and media streams between
30 different network technologies, such as from traditional Public Switched Telephone Network (PSTN)
to Voice over Internet Protocol (VoIP) networks. Further, the MGCF acts as a mediator, managing call setup, tear-down, and related signalling procedures between the Public Land Mobile Network (PLMN) and external networks.
35 [0078] Thereafter, the processing unit [304] is configured to identify, a rejected call cause code
associated with the rejected call, wherein the rejected call cause code comprises a rejected call SIP error response.
17

[0079] The present disclosure encompasses that the processing unit [304] may detect the rejected calls
by real time monitoring and analysing one or more signalling messages such as SIP signalling messages
which passes through one or more nodes for identifying the rejected call cause code that indicates the
5 rejected call SIP error response i.e., the reason of rejected call.
[0080] The present disclosure encompasses that the rejected call SIP error response may indicate a
reason associated with the rejected call based on detecting the rejected call cause code. The SIP is a
signalling protocol that is used for establishing, modifying, terminating one or more communication
10 sessions.
[0081] The present disclosure encompasses that the rejected call cause code includes but not limited
to 400 Bad Request, 401 Unauthorized, 402 Payment Requires, 404 Not Found. It is to be noted that
for above stated rejected call cause code are illustrative in nature and should not be interpreted as
15 limiting the scope of the disclosure.
[0082] The embodiments, examples, and descriptions herein are intended to facilitate understanding
and clarity regarding the disclosure. It is expressly stated that variations, modifications, and alternative
implementations that may be obvious to the person skilled in the art should be considered as falling
20 within the scope of the disclosure.
[0083] The present disclosure encompasses that to identify the rejected call cause code associated with the rejected call from the user equipment in the network, the processing unit [304] is further configured to determine an available rejected cause code status, wherein the available rejected cause code status is
25 determined based on receiving the rejected call cause code via the Session Initiation Protocol (SIP)
reason header. In an implementation of the present solution the available rejected cause code status may be determined based on matching the rejected call cause code and the list of ISUP cause codes. Further, the determination of the available rejected cause code status enables an improved categorization of the causes of call rejection which may assists in future call management, troubleshooting and network
30 optimization.
[0084] The present disclosure encompasses that the available rejected code status indicates that the status of the reject call cause codes that are available or accessible within the network.
35 [0085] Thereafter, the processing unit [304] is configured to determine, a cause code status associated
with the rejected call cause code based on matching the rejected call cause code and the list of ISUP
18

cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status.
[0086] The present disclosure encompasses that the positive cause code status is determined in an event
5 the rejected call cause code is a successful match with at least one of the ISUP cause code from the list
of ISUP cause codes. Further, as disclosed by the present disclosure, the negative cause code status is determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes from the list of ISUP cause codes.
10 [0087] Thereafter, the processing unit [304] is configured to identify, a target ISUP cause code from
the list of ISUP cause codes based on the positive cause code status. As disclosed by the present disclosure, the target ISUP cause code from the list of ISUP cause codes is identified in an event the rejected call cause code is a cause code that is present the list of ISUP cause codes i.e., the successful match of the rejected call cause code with the list of ISUP cause codes.
15
[0088] For instance, the target ISUP cause code is a specific cause code which is identified from the list of ISUP cause codes based on the positive cause code status. In an exemplary scenario, the target ISUP cause code may cause 1: Unallocated (unassigned) number based on the positive cause code status.
20
[0089] The present disclosure encompasses that the target ISUP code is a specific cause code that corresponds to the rejected call. Further, the identification of the target ISUP cause code allows to categorize the reason for the call rejection according to one or more ISUP signalling standards. Also, it is to be noted that the one or more ISUP cause codes may provide standardized explanations for various
25 call signalling events, such as call setup failure event or call release event, which helps in
interoperability and troubleshooting within networks.
[0090] Thereafter, the processing unit [304] is configured to generate, at the BGCF node [504] in the
network, the SIP error response associated with the target ISUP cause code based on identifying the
30 SIP error code associated with the target ISUP cause code.
[0091] The present disclosure encompasses that for generating the SIP error response associated with
the target ISUP cause code based on the identifying the SIP error code associated with the target ISUP
cause code, the processing unit [304] is further configured to change the rejected call SIP error response
35 to the SIP error response associated with the target ISUP cause code. Thus, for generating the SIP error
response, the rejected call SIP error response is changed to a corresponding SIP error response from the
19

list of SIP error responses, wherein the corresponding SIP error response is identified based on determining the corresponding SIP error response mapped with the target ISUP cause code.
[0092] The transceiver unit [302] is further configured to transmit, from the BGCF node [504] to the
5 target node in the network, the SIP error response based on the generated SIP error response.
[0093] The present disclosure encompasses that the transceiver unit [302] is further configured to
transmit, from the BGCF node [504], the rejected call SIP error response, in an event the negative cause
code status is detected. Further, as disclosed by the present disclosure, the negative cause code status is
10 determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP
codes from the list of ISUP cause codes.
[0094] The present disclosure encompasses that the rejected call SIP error response is transmitted by
the transceiver unit [302] from the BGCF node [504] in an event of determining an unsuccessful
15 receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header. The
unsuccessful receiving refers to the failure to receive the rejected call cause code via the SIP reason header.
[0095] Referring to FIG. 4, an exemplary method flow diagram [400] for transmitting a Session
20 Initiation Protocol (SIP) error response to a target node in a network in accordance with exemplary
implementations of the present disclosure is shown. In an implementation the method [400] is performed by the system [300]. Further, in an implementation, the system [300] may be present in a server device to implement the features of the present disclosure. Also, as shown in Figure 4, the method [400] starts at step [402]. 25
[0096] At step [404], the method [400] comprises receiving, by a transceiver unit [302] via an interface, a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses. 30
[0097] As used herein “SIP” is a signalling protocol used for initiating, maintaining, and terminating real-time communication sessions, such as voice call session and a video call session, in an IP Multimedia Subsystem (IMS).
35 [0098] As used herein “list of ISUP cause codes” are used in telecommunications networks to indicate
the reason for call failure or call disconnection. Each cause code represents a specific condition or event that led to the failure or disconnection. Further, list of ISUP cause codes may have one or more of cause
20

codes. Each ISUP cause code from the list of ISUP cause codes may indicate various condition such as
call failure, network congestion, subscriber unavailability, or signalling errors, enabling a network
operator in the telecommunication network to diagnose and troubleshoot the issue. Each ISUP cause
code from the list of ISUP cause codes corresponds to a specific scenario or event associated with the
5 call establishment or call disconnection in the telecommunication network.
[0099] As used herein “SIP error codes” are numeric codes used in SIP responses to indicate the status
of a request. The SIP error code provides information about whether the request was successful,
unsuccessful, or encountered an error. Each SIP error code from the list of SIP error code indicates a
10 failure or issue encountered during a communication session initiation process and/or a communication
session handling process. For instance, common SIP error codes include "404 Not Found," indicating that a requested resource was not found, and "503 Service Unavailable," indicating that a server cannot process the request at the moment due to overload and/or maintenance.
15 [0100] A SIP error response is a message sent by a SIP server to a client device such as a user device
in response to a failed SIP request and/or a failed SIP operation within a communication session. Each SIP error response from the list of SIP error responses provides a detailed information about the nature of the error encountered, helping the user device understand a reason of the failed SIP request and/or the failed SIP operation. Each SIP error code from the list of SIP error codes is associated with the one
20 or more SIP error responses from the list of SIP error responses and may include a Session Initiation
Protocol (SIP) reason header to provide context or suggestions for resolution of the failed SIP request and/or the failed SIP operation. Examples of SIP error responses include "401 Unauthorized," indicating that the user device needs authentication to proceed, and "500 Server Internal Error," indicating a problem on the server's end. At step [406], the method [400] comprises mapping, by a processing unit
25 [304] at a Breakout Gateway Control Function (BGCF) node [504] in the network, each ISUP cause
code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes.
30 [0101] As used herein “Breakout Gateway Control Function (BGCF)” is function that acts an interface
between one or more networks such as Public Switched Telephone Network (PSTN) network. The BGCF manage a routing of one or more calls that originate or terminate within the IP Multimedia Subsystem (IMS) network but need to be routed outside the IMS network. The BGCF serves as a bridge for ensuring a seamless communication between different types of networks.
35
21

[0102] At step [408], the method [400] comprises detecting, by the processing unit [304]at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network.
5 [0103] As used herein “Media Gateway Control Function (MGCF)” refers to a function that serves as
an interface between circuit-switched and packet-switched networks, facilitating seamless
communication between these distinct network domains. The MGCF is responsible for controlling
media gateways (MGWs), which perform the conversion of signalling and media streams between
different network technologies, such as from traditional Public Switched Telephone Network (PSTN)
10 to Voice over Internet Protocol (VoIP) networks. Further, the MGCF acts as a mediator, managing call
setup, tear-down, and related signalling procedures between the Public Land Mobile Network (PLMN) and external networks.
[0104] At step [410], the method [400] comprises identifying, by the processing unit [304], a rejected
15 call cause code associated with the rejected call, wherein the rejected call cause code comprises a
rejected call SIP error response.
[0105] The present disclosure encompasses that the processing unit [304] may detect the rejected calls
by real time monitoring and analysing one or more signalling messages such as SIP signalling messages
20 which passes through one or more nodes for identifying the rejected call cause code that indicates the
rejected call SIP error response i.e., the reason of rejected call.
[0106] The present disclosure encompasses that the rejected call SIP error response may indicate a
reason associated with the rejected call based on detecting the rejected call cause code. The SIP is a
25 signalling protocol that is used for establishing, modifying, terminating one or more communication
sessions.
[0107] The present disclosure encompasses that the rejected call cause code includes but not limited to 400 Bad Request, 401 Unauthorized, 402 Payment Requires, 404 Not Found. It is to be noted that
30 for above stated rejected call cause code are illustrative in nature and should not be interpreted as
limiting the scope of the disclosure. The embodiments, examples, and descriptions herein are intended to facilitate understanding and clarity regarding the disclosure. It is expressly stated that variations, modifications, and alternative implementations that may be obvious to the person skilled in the art should be considered as falling within the scope of the disclosure.
35
[0108] The present disclosure encompasses that identifying the rejected call cause code associated with the rejected call from the user equipment in the network further comprises determining, by the
22

processing unit [304], an available rejected cause code status, wherein the available rejected cause code status is determined based on receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
5 [0109] In an implementation of the present solution the available rejected cause code status may be
determined based on matching the rejected call cause code and the list of ISUP cause codes. Further,
the determination of the available rejected cause code status enables an improved categorization of the
causes of call rejection which may assists in future call management, troubleshooting and network
optimization.
10
[0110] The present disclosure encompasses that the available rejected code status indicates that the
status of the reject call cause codes that are available or accessible within the network.
[0111] At step [412], the method [400] comprises determining, by the processing unit [304], a cause
15 code status associated with the rejected call cause code based on matching the rejected call cause code
and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status.
[0112] The present disclosure encompasses that the positive cause code status is determined in an event
20 the rejected call cause code is a successful match with at least one of the ISUP cause code from the list
of ISUP cause codes. Further, as disclosed by the present disclosure, the negative cause code status is determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes from the list of ISUP cause codes.
25 [0113] At step [414], the method [400] comprises identifying, by the processing unit [304], a target
ISUP cause code from the list of ISUP cause codes based on the positive cause code status.
[0114] For instance, the target ISUP cause code is a specific cause code which is identified from the
list of ISUP cause codes based on the positive cause code status. In an exemplary scenario, the target
30 ISUP cause code may cause 1: Unallocated (unassigned) number based on the positive cause code
status.
[0115] As disclosed by the present disclosure, the target ISUP cause code from the list of ISUP cause
codes is identified in an event the rejected call cause code is a cause code that is present the list of ISUP
35 cause codes i.e., the successful match of the rejected call cause code with the list of ISUP cause codes.
23

[0116] The present disclosure encompasses that the target ISUP code is a specific cause code that
corresponds to the rejected call. Further, the identification of the target ISUP cause code allows to
categorize the reason for the call rejection according to one or more ISUP signalling standards. Also, it
is to be noted that the one or more ISUP cause codes may provide standardized explanations for various
5 call signalling events, such as call setup failure event or call release event, which helps in
interoperability and troubleshooting within networks.
[0117] At step [416], the method [400] comprises generating, by the processing unit [304] at the BGCF
node [504] in the network, the SIP error response associated with the target ISUP cause code based on
10 identifying the SIP error code associated with the target ISUP cause code.
[0118] The present disclosure encompasses that the generating the SIP error response associated with
the target ISUP cause code based on the identifying the SIP error code associated with the target ISUP
cause code, further comprises changing, by the processing unit [304], the rejected call SIP error
15 response to the SIP error response associated with the target ISUP cause code.
[0119] Thus, for generating the SIP error response, the rejected call SIP error response is changed to a
corresponding SIP error response from the list of SIP error responses, wherein the corresponding SIP
error response is identified based on determining the corresponding SIP error response mapped with
20 the target ISUP cause code.\At step [418], the method [400] comprises transmitting, by the transceiver
unit [302] from the BGCF node [504] to the target node in the network, the SIP error response based on the generating the SIP error response.
[0120] The present disclosure encompasses that the method further comprises transmitting, by the
25 transceiver unit [302] from the BGCF node [504], the rejected call SIP error response, in an event the
negative cause code status is detected. Further, as disclosed by the present disclosure, the negative cause code status is determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes from the list of ISUP cause codes.
30 [0121] The present disclosure encompasses that the rejected call SIP error response is transmitted by
the transceiver unit [302] from the BGCF node [504], in an event of determining an unsuccessful receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
[0122] The method [400] terminates at step [420]. 35
[0123] Referring to FIG. 5, exemplary network environment diagram [500] for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, in accordance with exemplary
24

implementations of the present disclosure is shown. As depicted in FIG. 5, a Serving-Call Session
Control Function (S-CSCF) node [502] in connection with a Breakout Gateway Control Function
(BGCF) node [504]. The S-CSCF node [502] is the target node. Further, a Media Gateway Control
Function (MGCF) node [506] is also in connection with the BGCF node [504]. The BGCF node [504]
5 acts as a vital intermediary between the MGCF node [506] and the S-CSCF node [502], seamlessly
translating the received Q.850 code i.e., Q.850 cause codes on a Mj interface [508] from the MGCF
node [506] into the mapped SIP error code before forwarding to the S-CSCF [502] on a Mi interface
[510] to ensure smooth and accurate conversion, thereby improving interoperability and overall network
reliability. By maintaining an up-to-date mapping of cause codes, the BGCF node [504] facilitates
10 efficient communication between ISUP and SIP networks, enhancing the overall performance of the
network.
[0124] Additionally, Q.850 cause code is standard code used in the telecommunication network for
indicating a reason for call establishment failures or call disconnection reasons. Moreover, the Q.850
15 cause code is a numeric identifier which denotes the reason for call establishment failures or call
disconnection failure. For example, Q.850 Cause Code 16 denotes Normal call clearing; Q.850 Cause Code 34 denotes No circuit/channel available; Q.850 Cause Code 38 denotes Network out of order, etc.
20 [0125] A cause code provides an information on the cause of error. For instance, code 1 in Q.850 cause
code indicates that the error was due to an ‘unallocated number’, code 2 in Q.850 cause code indicates that there is ‘no route to transit network’.
[0126] Further, the Mi interface [510] is an interface that represents the communication link between
25 the BGCF node [504] and the S-CSCF node [502]. The Mj interface [508] is an interface that represents
communication link between the BGCF node [504] and the MGCF node [506]. The Mi interface [510]
and Mj interface [508] facilitates an exchange of one or more signalling messages for call control and
session management between the BGCF node [504] and the MGCF node [506] such as messages
associated with a Session Initiation Protocol (SIP) and a Service Delivery Platform (SDP) of the
30 network for the purpose of internetworking between a circuit switched networks.
[0127] As used herein, “Session Initiation Protocol (SIP)” is s a signalling protocol that is utilized for initiating, maintaining, modifying and terminating one or more real-time communications sessions between one or more Internet Protocol (IP) devices. 35
[0128] As used herein, “Service Delivery Platform (SDP)” is a set of components which provide one or more service(s) to one or more subscribers or customers. Moreover, the SDP acts an interface
25

between a network infrastructure and one or more service applications for enabling efficient management and delivery of the one or more service(s).
[0129] As used herein “Breakout Gateway Control Function (BGCF)” is function that acts an interface
5 between one or more networks such as Public Switched Telephone Network (PSTN) network. The
BGCF manage a routing of one or more calls that originate or terminate within the IP Multimedia Subsystem (IMS) network but need to be routed outside the IMS network. The BGCF serves as a bridge for ensuring a seamless communication between different types of networks.
[0130] As used herein “Media Gateway Control Function (MGCF)” refers to a function that serves as an interface between circuit-switched and packet-switched networks, facilitating seamless communication between these distinct network domains. The MGCF is responsible for controlling media gateways (MGWs), which perform the conversion of signalling and media streams between different network technologies, such as from traditional Public Switched Telephone Network (PSTN) to Voice over Internet Protocol (VoIP) networks. Further, the MGCF acts as a mediator, managing call setup, tear-down, and related signalling procedures between the Public Land Mobile Network (PLMN) and external networks.
[0131] As used herein, the Serving-Call Session Control Function (S-CSCF) of an IP Multimedia Subsystem (IMS) architecture is configured to manage session control for multimedia services. Further, the S-CSCF may handle the establishment, modification, and termination of multimedia sessions, ensuring efficient communication between users over IP networks. Further, the S-CSCF may interact with the Home Subscriber Server (HSS) to retrieve user profiles and subscription information, facilitating personalized service delivery and authentication. Further, the S-CSCF enforces service policies and rules, ensuring the consistent delivery of services according to user preferences and network configurations.
[0132] Referring to FIG. 6, a flow diagram [600] for transmitting a Session Initiation Protocol (SIP)
error response to a target node in a network in accordance with exemplary implementations of the
30 present disclosure is shown.
[0133] At step S1, an Integrated Services Digital Network User Part (ISUP) code (q.850 cause code) is mapped to a SIP error response at Breakout Gateway Control Function (BGCF) node [504] in the network. 35
[0134] At step S2, in an event an offnet call gets rejected by the Media Gateway Control Function (MGCF) node [506].
26

[0135] Thereafter, at step S3, the availability of the ISUP code is assessed i.e., if the ISUP code
associated with the offnet call reject event is available in a list of ISUP cause codes. If available, Step
S4 examines whether the received ISUP code is mapped with an error response within the BGCF node
5 [504].
[0136] In a scenario if the received ISUP code is mapped within the BGCF node [504], then at Step S5, the received SIP error is transformed into the mapped error response, which is then transmitted to the Serving-Call Session Control Function (S-CSCF) node [502].
10
[0137] Additionally, at step S3, if the ISUP code is unavailable, then at step S6 i.e., if the ISUP code associated with the offnet call reject event not available in the list of ISUP cause codes. In such a scenario, at step S6 the received response is relayed to the S-CSCF node [502]. Also, at step S4, if the received ISUP code is not mapped with the error response in the BGCF node [504], then the method
15 performs the Step S6 i.e., the received response is relayed to the S-CSCF node [502].
[0138] The present disclosure further discloses a user equipment (UE) for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, the UE comprising a memory, and a processor coupled to the memory. Further, the processor is configured to transmit, to a system [300]
20 via an interface, at least one of: a list of Integrated Services Digital Network User Part (ISUP) cause
codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses, and receive, from the system [300], an SIP error response based on at least one of the list of ISUP cause codes, a list of SIP error codes and a list of SIP error responses.
25 Further, the SIP error response is received based on mapping, by the system [300] at a Breakout
Gateway Control Function (BGCF) node [504] in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes. Further, the SIP error response is received based on detecting, by the system [300] at a Media Gateway Control Function
30 (MGCF) node [506] in the network, a rejected call from a user equipment in the network. Further, the
SIP error response is received based on identifying, by the system [300], a rejected call cause code associated with the rejected call. Further, the SIP error response is received based on determining, by the system [300], a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a
35 positive cause code status and a negative cause code status. Further, the SIP error response is received
based on identifying, by the system [300], a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status. Further, the SIP error response is received based on generating,
27

by the system [300] at the BGCF node [504] in the network, the SIP error response associated with the
target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause
code. Thereafter, the SIP error response is received based on transmitting, by the system [300] from the
BGCF node [504] to the target node in the network, the SIP error response based on the generating the
5 SIP error response.
[0139] The present disclosure further discloses a non-transitory computer readable storage medium storing instructions for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network the instructions include executable code which, when executed by one or more units of a
10 system [300], causes a transceiver unit [302] of the system to receive, via an interface, a list of Integrated
Services Digital Network User Part (ISUP) cause codes, a list Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses. The executable code when executed causes a processing unit [304] of the system to map, at a Breakout Gateway Control
15 Function (BGCF) node [504] in the network, each ISUP cause code from the list of ISUP cause codes
with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes. The executable code when executed causes the processing unit [304] to detect at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network. The executable code when executed
20 causes the processing unit [304] to identify, a rejected call cause code associated with the rejected call,
wherein the rejected call cause code comprises a rejected call SIP error response. The executable code when executed causes the processing unit [304] to determine, a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status.
25 The executable code when executed causes the processing unit [304] to identify, a target ISUP cause
code from the list of ISUP cause codes based on the positive cause code status. Further, the executable code when executed causes the processing unit [304] to generate, at the BGCF node [504] in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code. Thereafter, the executable code when
30 executed causes the transceiver unit [302] to transmit, from the BGCF node [504] to the target node in
the network, the SIP error response based on the generated SIP error response.
[0140] As is evident from the above, the present disclosure provides a technically advanced solution
for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network. The
35 present solution utilizes a Breakout Gateway Control Function (BGCF) node to dynamically map each
Integrated Services Digital Network User Part (ISUP) cause code to one or more Session Initiation Protocol (SIP) error codes. The present solution detects and identifies the rejected calls from user
28

equipment within the network, which enables to promptly recognize call failures and initiate appropriate
responses. Upon identifying the rejected call cause code, the present solution determines the cause code
status by matching with a list of ISUP cause codes. This determination helps categorize the reason for
the call rejection, providing valuable insights for troubleshooting and optimization. Further, If the cause
5 code status is positive, indicating a match with an ISUP cause code, the present solution identifies the
specific target ISUP cause code associated with the rejected call. This precise identification facilitates
accurate handling and resolution of call failures. Based on the identified target ISUP cause code, the
present solution generates the corresponding SIP error response at the BGCF node. Subsequently, the
transceiver unit transmits this SIP error response to the target node in the network. The present solution
10 ensures that appropriate error responses are promptly delivered, facilitating effective communication
and troubleshooting.
[0141] While considerable emphasis has been placed herein on the disclosed implementations, it will
be appreciated that many implementations can be made and that many changes can be made to the
15 implementations without departing from the principles of the present disclosure. These and other
changes in the implementations of the present disclosure will be apparent to those skilled in the art, whereby it is to be understood that the foregoing descriptive matter to be implemented is illustrative and non-limiting.
20
29

We Claim:
1. A method [400] for transmitting a Session Initiation Protocol (SIP) error response to a target node
in a network, the method comprising:
- receiving, by a transceiver unit [302] via an interface, at least one of: a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses;
- mapping, by a processing unit [304] at a Breakout Gateway Control Function (BGCF) node [504] in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes;
- detecting, by the processing unit [304] at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network;
- identifying, by the processing unit [304], a rejected call cause code associated with the rejected call;
- determining, by the processing unit [304], a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status;
- identifying, by the processing unit [304], a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status;
- generating, by the processing unit [304] at the BGCF node [504] in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code; and
- transmitting, by the transceiver unit [302] from the BGCF node [504] to the target node in the network, the SIP error response based on the generating the SIP error response.
2. The method [400] as claimed in claim 1, wherein the positive cause code status is determined in
an event the rejected call cause code is a successful match with at least one of the ISUP cause
code from the list of ISUP cause codes, and wherein the negative cause code status is determined
in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes
from the list of ISUP cause codes.

3. The method [400] as claimed in claim 2, wherein the method [400] further comprises transmitting, by the transceiver unit [302] from the BGCF node [504], the rejected call SIP error response, in an event the negative cause code status is detected.
4. The method [400] as claimed in claim 1, wherein the generating the SIP error response associated with the target ISUP cause code based on the identifying the SIP error code associated with the target ISUP cause code further comprises:
- changing, by the processing unit [304], the rejected call SIP error response to the SIP error
response associated with the target ISUP cause code.
5. The method [400] as claimed in claim 1, wherein identifying the rejected call cause code associated with the rejected call from the user equipment in the network further comprises determining, by the processing unit [304], an available rejected cause code status, wherein the available rejected cause code status is determined based on receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
6. The method [400] as claimed in claim 5, wherein the rejected call SIP error response is transmitted by the transceiver unit [302] from the BGCF node [504], in an event of determining an unsuccessful receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
7. The method [400] as claimed in claim 1, wherein the rejected call cause code comprises a rejected call SIP error response.
8. A system [300] for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, the system [300] comprises:
- a transceiver unit [302], wherein the transceiver unit [302] is configured to:
• receive, via an interface, a list of Integrated Services Digital Network User Part (ISUP)
cause codes, a list Session Initiation Protocol (SIP) error codes and a list of SIP error
responses, wherein each SIP error code from the list of SIP error codes is associated with
one or more SIP error responses from the list of SIP error responses; and
a processing unit [304] connected to at least the transceiver unit [302], wherein the processing unit [304] configured to:
• map, at a Breakout Gateway Control Function (BGCF) node [504] in the network, each
ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes,

wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes,
• detect, at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network,
• identify, a rejected call cause code associated with the rejected call;
• determine, a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status,
• identify, a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status,
• generate, at the BGCF node [504] in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code; and
wherein the transceiver unit [302] is further configured to:
• transmit, from the BGCF node [504] to the target node in the network, the SIP error
response based on the generated SIP error response.
9. The system [300] as claimed in claim 8, wherein the positive cause code status is determined in an event the rejected call cause code is a successful match with at least one of the ISUP cause code from the list of ISUP cause codes, and wherein the negative cause code status is determined in an event the rejected call cause code is an unsuccessful match with each of the ISUP codes from the list of ISUP cause codes.
10. The system [300] as claimed in claim 9, wherein the transceiver unit [302] is further configured to transmit, from the BGCF node [504], the rejected call SIP error response, in an event the negative cause code status is detected.
11. The system [300] as claimed in claim 8, wherein for generating the SIP error response associated with the target ISUP cause code based on the identifying the SIP error code associated with the target ISUP cause code, the processing unit [304] is further configured to:
- change the rejected call SIP error response to the SIP error response associated with the target
ISUP cause code.
12. The system [300] as claimed in claim 8, wherein to identify the rejected call cause code associated
with the rejected call from the user equipment in the network, the processing unit [304] is further
configured to determine an available rejected cause code status, wherein the available rejected

cause code status is determined based on receiving the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
13. The system [300] as claimed in claim 12, wherein the rejected call SIP error response is transmitted by the transceiver unit [302] from the BGCF node [504] in an event of determining an unsuccessful receiving of the rejected call cause code via the Session Initiation Protocol (SIP) reason header.
14. The system [300] as claimed in claim 8, wherein the rejected call cause code comprises a rejected call SIP error response.
15. A User Equipment (UE) for transmitting a Session Initiation Protocol (SIP) error response to a target node in a network, the UE comprising:

- a memory; and
- a processor coupled to the memory, wherein the processor is configured to:
o transmit, to a system [300] via an interface, at least one of: a list of Integrated Services Digital Network User Part (ISUP) cause codes, a list of Session Initiation Protocol (SIP) error codes and a list of SIP error responses, wherein each SIP error code from the list of SIP error codes is associated with one or more SIP error responses from the list of SIP error responses, and
o receive, from the system [300], an SIP error response based on at least one of the list of ISUP cause codes, a list of SIP error codes and a list of SIP error responses,
wherein the SIP error response is received based on:
mapping, by the system [300] at a Breakout Gateway Control Function (BGCF) node [504] in the network, each ISUP cause code from the list of ISUP cause codes with the one or more SIP error codes, wherein said each ISUP cause code is mapped with at least the SIP error response associated with the one or more SIP error codes,
detecting, by the system [300] at a Media Gateway Control Function (MGCF) node [506] in the network, a rejected call from a user equipment in the network,
identifying, by the system [300], a rejected call cause code associated with the rejected call,

determining, by the system [300], a cause code status associated with the rejected call cause code based on matching the rejected call cause code and the list of ISUP cause codes, wherein the cause code status is one of a positive cause code status and a negative cause code status,
identifying, by the system [300], a target ISUP cause code from the list of ISUP cause codes based on the positive cause code status,
generating, by the system [300] at the BGCF node [504] in the network, the SIP error response associated with the target ISUP cause code based on identifying the SIP error code associated with the target ISUP cause code, and
transmitting, by the system [300] from the BGCF node [504] to the target node in the network, the SIP error response based on the generating the SIP error response.