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 SESSION
INITIATION PROTOCOL REQUEST TO HOME
SUBSCRIBER SERVER”
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 SESSION INITIATION PROTOCOL REQUEST TO HOME SUBSCRIBER SERVER
TECHNICAL FIELD
[0001] Embodiments of the present disclosure generally relate to wireless communication systems. More particularly, embodiments of the present disclosure relate to method and system for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS).
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 IP Multimedia core network system (IMS), Interrogating-Call Session Control Function (I-CSCF) and Serving-Call Session Control Function (S-CSCF) communicate with Home Subscriber Server (HSS) on Cx interface over the Diameter protocol for getting the user profile. The diameter protocol is a point-to-point protocol, and it is routed based on the Destination-Realm Attribute Value Pair (AVP) sent in the diameter message. The Destination-Realm AVP is used to identify the realm (or domain) of the recipient, which is used for authentication, authorization and accounting (AAA) services in a diameter protocol. Further, the AVP is a protocol in telecom standards which is used for routing the diameter traffic to the correct destination.
[0005] In IMS, I-CSCF and S-CSCF serve as a home for the subscriber. So, requests coming from any Public Land Mobile Network (PLMN) (circle) for the subscriber should be treated as home and must be routed to the subscriber's PLMN HSS only. These network elements can also be deployed in multi-PLMNs (circles) that serve as the home for the multiple circles.
[0006] When I-CSCF and S-CSCF are serving multiple PLMNs and there are different HSS in the network, then I-CSCF and S-CSCF are required to connect to the HSS. And while sending the Cx request for the user, these nodes should select the correct HSS, otherwise, the user data will not be available, and the request will get rejected by another HSS. This is a major challenge in multi-circle IMS core deployment.
[0007] Further, over the period of time various solutions have been developed to improve the performance of communication devices and to select a Home Subscriber Server (HSS). However, there are certain challenges with existing solutions such as it does not provide any solution for the limitations of the diameter

protocol, which is a point-to-point protocol used for communication between I-CSCF, S-CSCF, and HSS in the IMS core network. The diameter protocol relies on the Destination-Realm AVP for routing, which may not be sufficient for ensuring accurate routing to the subscriber's PLMN HSS when requests are coming from various PLMNs. Additionally, the existing solutions fail to address the complexities that arise when I-CSCF and S-CSCF serve multiple PLMNs, each with their own HSS. There are various challenges faced in connecting to multiple HSSs and the selection process for choosing the correct HSS when sending Cx requests.
[0008] Thus, there exists an imperative need in the art to address the above-mentioned problems in the prior art.
SUMMARY
[0009] 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.
[0010] An aspect of the present disclosure may relate to a method for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS). The method comprises receiving, by a transceiver unit, a set of network data associated with a network. It is to be noted that the set of network data comprises a set of plurality of public land mobile network (PLMN) associated with the network and a set of HSS associated with the network. It is further noted that each PLMN from the set of plurality of PLMN is associated with at least one HSS from the set of HSS. The method further comprises receiving, by the transceiver unit, at a System Information Blocks (SIB) in the network, the Session Initiation Protocol (SIP) request. The method further comprises identifying, by an identification unit, at the SIB in the network, a target SIP request based on the SIP request. It is to be noted that the target SIP request comprises one or more target SIP data fields. The

method further comprises extracting, by an extraction unit, a domain information associated with the target SIP request based on the one or more target SIP data fields. The method further comprises determining, by a determination unit, a target PLMN from the set of plurality of PLMN based on the domain information. The method further comprises identifying, by the identification unit, the target HSS from the set of HSS associated with the target PLMN based on the domain information. The method further comprises transmitting, by the transceiver unit, the target SIP request to the target HSS based on identifying the target HSS.
[0011] In an exemplary aspect of the present disclosure, the SIP request is at least one of a register SIP request, an originating SIP request, and a terminating SIP request.
[0012] In an exemplary aspect of the present disclosure, the one or more target SIP data fields associated with the register SIP request comprise at least a username parameter.
[0013] In an exemplary aspect of the present disclosure, the one or more target SIP data fields associated with the originating SIP request comprise at least one of a P-Asserted-Identity header and a from header.
[0014] In an exemplary aspect of the present disclosure, the one or more target SIP data fields associated with the terminating SIP request comprise at least a Request-URI (R-URI).
[0015] In an exemplary aspect of the present disclosure, the P-Asserted-Identity header associated with the originating SIP request is in a predefined format.
[0016] In an exemplary aspect of the present disclosure, the target SIP request is transmitted to the target HSS via an interface in the network, wherein the target SIP request further comprises a Destination-Realm Attribute Value Pair (AVP).

[0017] Another aspect of the present disclosure may relate to a system for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS). The system further comprises a transceiver unit configured to receive a set of network data associated with a network. It is to be noted that the set of network data comprises a set of plurality of public land mobile network (PLMN) associated with the network, and a set of HSS associated with the network. It is further noted that each PLMN from the set of plurality of PLMN is associated with at least one HSS from the set of HSS. The transceiver unit is further configured to receive, at a System Information Blocks (SIB) in the network, the Session Initiation Protocol (SIP) request. The system further comprise an identification unit connected to at least the transceiver unit, the identification unit is configured to identify, at the SIB in the network, a target SIP request based on the SIP request, wherein the target SIP request comprises one or more target SIP data fields. The system further comprises an extraction unit connected to at least the identification unit, the extraction unit is configured to extract, a domain information associated with the target SIP request based on the one or more target SIP data fields. The system further comprises a determination unit connected to at least the extraction unit, the determination unit configured to determine a target PLMN from the set of plurality of PLMN based on the domain information. The identification unit is further configured to identify, the target HSS from the set of HSS associated with the target PLMN. The transceiver unit is further configured to transmit the target SIP request to the target HSS based on identifying the target HSS.
[0018] An another aspect of the present disclosure may relate to a non-transitory computer-readable storage medium storing instruction for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS), the storage medium comprising executable code which, when executed by one or more units of a system, causes a transceiver unit of the system to receive, a set of network data associated with a network, wherein the set of network data comprises a set of plurality of public land mobile network (PLMN) associated with the network, and

a set of HSS associated with the network, and wherein each PLMN from the set of plurality of PLMN is associated with at least one HSS from the set of HSS. The instructions further include executable code which, when executed, causes the transceiver unit to receive, at a System Information Blocks (SIB) in the network, the Session Initiation Protocol (SIP) request. The instructions further include executable code which, when executed, causes an identification unit of the system to identify, at the SIB in the network, a target SIP request based on the SIP request, wherein the target SIP request comprises one or more target SIP data fields. The instructions further include executable code which, when executed, causes an extraction unit of the system to extract, a domain information associated with the target SIP request based on the one or more target SIP data fields. The instructions further include executable code which, when executed, causes a determination unit of the system to determine, a target PLMN from the set of plurality of PLMN based on the domain information. The instructions further include executable code which, when executed, causes the identification unit to further identify, the target HSS from the set of HSS associated with the target PLMN; and the transceiver unit to further transmit, the target SIP request to the target HSS based on identifying the target HSS.
OBJECTS OF THE DISCLOSURE
[0019] Some of the objects of the present disclosure, which at least one embodiment disclosed herein satisfies are listed herein below.
[0020] It is an object of the present disclosure to provide a system and a method for efficiently selecting a Home Subscriber Server (HSS).
[0021] It is another object of the present disclosure to provide a solution to enable I-CSCF (Interrogating Call Session Control Function) and S-CSCF (Serving Call Session Control Function) to efficiently serve multiple circles.

[0022] It is yet another object of the present disclosure to provide a solution to enhance network performance, resource utilization, and scalability by providing a reliable and versatile solution that optimally utilizes IMS Core elements, resulting in improved service delivery and efficient management of multi-circle IMS core networks.
DESCRIPTION OF THE DRAWINGS
[0023] 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 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 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.
[0024] FIG. 1 illustrates an exemplary block diagram representation of 5th generation core (5GC) network architecture.
[0025] 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.
[0026] FIG. 3 illustrates an exemplary block diagram of a system for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS), in accordance with exemplary implementations of the present disclosure.

[0027] FIG. 4 illustrates a method flow diagram for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS) in accordance with exemplary implementations of the present disclosure.
5 [0028] FIG. 5 illustrates an exemplary architecture diagram of a system for
automatically transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS), in accordance with exemplary embodiments of the present disclosure.
10 [0029] FIG. 6 depicting an exemplary scenario flow diagram for automatically
transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS), in accordance with exemplary embodiments of the present disclosure.
15 [0030] The foregoing shall be more apparent from the following more detailed
description of the disclosure.
DETAILED DESCRIPTION
20 [0031] 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
25 another or with any 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.
[0032] The ensuing description provides exemplary embodiments only, and is not
30 intended to limit the scope, applicability, or configuration of the disclosure. Rather,
the ensuing description of the exemplary embodiments will provide those skilled in
9

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. 5
[0033] Specific details are given in the following description to provide a thorough
understanding of 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
10 may be shown as components in block diagram form in order not to obscure the
embodiments in unnecessary detail.
[0034] 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
15 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 a figure.
20
[0035] 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 “demonstrative” is not
25 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
30 similar to the term “comprising” as an open transition word—without precluding
any additional or other elements.
10

[0036] 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
5 purpose processor, a conventional processor, a digital signal processor, a plurality
of microprocessors, one or more microprocessors in association with a (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,
10 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.
[0037] As used herein, “a user equipment”, “a user device”, “a smart-user-device”,
15 “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
user equipment/device may include, but is not limited to, a mobile phone, smart
20 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
25 such unit(s) which are required to implement the features of the present disclosure.
[0038] 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
30 medium includes read-only memory (“ROM”), random access memory (“RAM”),
magnetic disk storage media, optical storage media, flash memory devices or other
11

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.
5 [0039] As used herein “interface” or “user interface refers to a shared boundary
across which two or 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
10 called.
[0040] 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,
15 a digital signal processor (DSP), a plurality of microprocessors, 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.
20 [0041] 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.
25 [0042] Home Subscriber Server (HSS) is a crucial component within the IMS (IP
Multimedia Subsystem) core network architecture. It is a centralized database that stores and manages subscriber-related information and user profiles. The HSS acts as the repository for subscriber data, including authentication credentials, service subscriptions, location information, and session preferences. It serves as the
30 authoritative source for authenticating and authorizing subscriber access to services
and resources within the network. The HSS plays a vital role in facilitating
12

subscriber mobility and seamless communication by ensuring the correct routing of
requests and providing the necessary subscriber information to other network
elements such as I-CSCF (Interrogating Call Session Control Function) and S-
CSCF (Serving Call Session Control Function). In multi-circle IMS core
5 deployments, the HSS is responsible for managing multiple PLMNs (Public Land
Mobile Networks) and maintaining accurate subscriber profiles for each respective home circle.
[0043] As discussed in the background section, the current known solutions have
10 several shortcomings. The present disclosure aims to overcome those shortcomings
and other existing problems in this field of technology by providing method and
system of transmitting a Session Initiation Protocol (SIP) request to a target Home
Subscriber Server (HSS). Also, the current known solutions have several
shortcomings such as it does not provide any solution for the limitations of the
15 diameter protocol, which is a point-to-point protocol used for communication
between I-CSCF, S-CSCF, and HSS in the IMS core network. The diameter
protocol relies on the Destination-Realm AVP for routing, which may not be
sufficient for ensuring accurate routing to the subscriber's PLMN HSS when
requests are coming from various PLMNs. Additionally, the prior known solutions
20 fail to address the complexities that arise when I-CSCF and S-CSCF serve multiple
PLMNs, each with their own HSS. There are various challenges faced in connecting to multiple HSSs and the selection process for choosing the correct HSS when sending Cx requests.
25 [0044] The present disclosure discloses a novel solution to accurately identify the
home circle HSS (Home Subscriber Server) of a subscriber by extracting the PLMN (Public Land Mobile Network) information from the received SIP (Session Initiation Protocol) request. This is achieved by analyzing various headers within the SIP request. The PLMN information is extracted from key headers, including
30 the P-Asserted-Identity header, the username in the Authorization header, the From
header, and the Request URI (R-URI). By employing I-CSCF (Interrogating Call
13

Session Control Function) and S-CSCF (Serving Call Session Control Function)
with dedicated diameter routing logic for each serving PLMN, the proposed
solution enables the selection of the correct HSS based on the extracted PLMN
information. It is to be noted that user home information and diameter agent (within
5 the S-CSCF or external Diameter routing agent [DRA]) has a configuration of
correct HSS for each realm, which is used to identify the correct HSS. This approach ensures accurate identification of the home circle HSS, facilitating seamless communication and enhanced network management for subscribers in a reliable and efficient manner. 10
[0045] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.
[0046] FIG. 1 illustrates an exemplary block diagram representation of 5th
15 generation core (5GC) network architecture [100], 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 network
(RAN) [104], an access and mobility management function (AMF) [106], a Session
Management Function (SMF) [108], a Service Communication Proxy (SCP) [110],
20 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 (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
25 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.
[0047] The Radio Access Network (RAN) [104] is the part of a mobile
30 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).
14

It consists of radio base stations and the radio access technologies that enable wireless communication.
[0048] The Access and Mobility Management Function (AMF) [106] is a 5G core
5 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.
[0049] The Session Management Function (SMF) [108] is a 5G core network
10 function responsible for managing session-related aspects, such as establishing,
modifying, and releasing sessions. It coordinates with the User Plane Function
(UPF) for data forwarding and handles IP address allocation and QoS enforcement.
[0050] The Service Communication Proxy (SCP) [110] is a network function in the
15 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.
[0051] The Authentication Server Function (AUSF) [112] is a network function in
20 the 5G core responsible for authenticating UEs during registration and providing
security services. It generates and verifies authentication vectors and tokens.
[0052] The Network Slice Specific Authentication and Authorization Function
(NSSAAF) [114] is a network function that provides authentication and
25 authorization services specific to network slices. It ensures that UEs can access only
the slices for which they are authorized.
[0053] The Network Slice Selection Function (NSSF) [116] is a network function
responsible for selecting the appropriate network slice for a UE based on factors
30 such as subscription, requested services, and network policies.
15

[0054] The 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.
5 [0055] The Network Repository Function (NRF) [120] is a network function that
acts as a central repository for information about available network functions and services. It facilitates the discovery and dynamic registration of network functions.
[0056] The Policy Control Function (PCF) [122] is a network function responsible
10 for policy control decisions, such as QoS, charging, and access control, based on
subscriber information and network policies.
[0057] The Unified Data Management (UDM) [124] is a network function that
centralizes the management of subscriber data, including authentication,
15 authorization, and subscription information.
[0058] The Application Function (AF) [126] is a network function that represents external applications interfacing with the 5G core network to access network capabilities and services. 20
[0059] The User Plane Function (UPF) [128] is a network function responsible for handling user data traffic, including packet routing, forwarding, and QoS enforcement.
25 [0060] The Data Network (DN) [130] refers to a network that provides data
services to user equipment (UE) in a telecommunications system. The data services may include but are not limited to Internet services, private data network related services.
30 [0061] The present disclosure can be implemented on a computing device [200] as
shown in FIG. 2. The computing device [200] is in accordance with the 5G
16

communication network architecture 100 (as shown in Fig. 1). FIG. 2 illustrates an
exemplary block diagram of the 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
5 device [200] may also implement a method for transmitting a Session Initiation
Protocol (SIP) request to a target Home Subscriber Server (HSS) utilising the
system. In another implementation, the computing device [200] itself implements
the method for transmitting a Session Initiation Protocol (SIP) request to a target
Home Subscriber Server (HSS) using one or more units configured within the
10 computing device [200], wherein said one or more units are capable of
implementing the features as disclosed in the present disclosure.
[0062] The computing device [200] may include a bus [202] or other communication mechanism for communicating information, and a hardware
15 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 (RAM), or other dynamic storage device, coupled to the bus [202] for storing information and instructions to be executed by the processor [204]. The
20 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 that is customized to perform the operations specified in the
25 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].
[0063] A storage device [210], such as a magnetic disk, optical disk, or solid-state
30 drive is provided and coupled to the bus [202] for storing information and
instructions. The computing device [200] may be coupled via the bus [202] to a
17

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
5 bus [202] for communicating information and command 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]. Th input device typically has two degrees
10 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.
[0064] The computing device [200] may implement the techniques described herein using customized hard-wired logic, one or more ASICs or FPGAs, firmware
15 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 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
20 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 may be used in place of or in combination with
25 software instructions.
[0065] 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
30 local network [222]. For example, the communication interface [218] may be an
integrated services digital network (ISDN) card, cable modem, satellite modem, or
18

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
5 implementation, the communication interface [218] sends and receives electrical,
electromagnetic or optical signals that carry digital data streams representing various types of information.
[0066] The computing device [200] can send messages and receive data, including
10 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 [228], the
ISP [226], the host [224], the local network [222] and the communication interface
[218]. The received code may be executed by the processor [204] as it is received,
15 and/or stored in the storage device [210], or other non-volatile storage for later
execution.
[0067] The present disclosure is implemented by a system [300] (as shown in FIG. 3). The computing device [200] (as shown in Fig. 2) may include said system [300].
20 In an implementation, the computing device [200] may be connected to the system
[300] to perform the present disclosure. Referring to FIG. 3, an exemplary block diagram of the system [300] for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS) [300T], is shown, in accordance with the exemplary implementations of the present disclosure. The system [300]
25 comprises at least one transceiver unit [301], at least one identification unit [302],
at least one extraction unit [303], and at least one determination unit [304] connected to a network [300N]. The network [300N] further comprises a set of plurality of public land mobile network (PLMN) [300PN], a set of HSS [300S], a system information block (SIB) [300Ns] and interface [305]. In an implementation,
30 the SIB comprises of the I-CSCF, S-CSCF and B-CSCF. Also, all of the
components/ units of the system [300] are assumed to be connected to each other
19

unless otherwise indicated below. As shown in the figures all units shown within
the system should also be assumed to 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
5 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. The system [300] may be in communication with the user device/ equipment (may also referred herein as a UE). Further, in an implementation, the interface [305] may form part of the system [300]. 10
[0068] The system [300] is configured for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS) [300T], with the help of the interconnection between the components/units of the system [300].
15 [0069] The transceiver unit [301] is configured to receive a set of network data
associated with a network [300N]. It is to be noted that the set of network data comprises a set of plurality of public land mobile network (PLMN) [300PN] associated with the network [300N], and a set of HSS [300S] associated with the network [300N]. It is further noted that each PLMN from the set of plurality of
20 PLMN [300PN] is associated with at least one HSS from the set of HSS [300S].
The transceiver unit [301] is further configured to receive, at a System Information Blocks (SIB) [300Ns] in the network [300N], the Session Initiation Protocol (SIP) request. It is to be noted that the SIB [300Ns] are broadcast messages that are sent from gNodeB to the UEs that contain essential information about the ongoing
25 session.
[0070] In an exemplary embodiment of the present disclosure, the SIP request is at least one of a register SIP request, an originating SIP request, and a terminating SIP request. 30
20

[0071] The identification unit [302] is configured to identify, at the SIB [300Ns] in
the network [300N], a target SIP request based on the SIP request, wherein the
target SIP request comprises one or more target SIP data fields. In an exemplary
embodiment of the present disclosure, the one or more target SIP data fields
5 associated with the register SIP request comprise at least a username parameter. In
an exemplary embodiment of the present disclosure, the one or more target SIP data
fields associated with the originating SIP request comprise at least one of a P-
Asserted-Identity header and a from header. In an exemplary embodiment of the
present disclosure, the one or more target SIP data fields associated with the
10 terminating SIP request comprise at least a Request-URI (R-URI). In an exemplary
embodiment of the present disclosure, the P-Asserted-Identity header associated with the originating SIP request is in a predefined format.
[0072] The extraction unit [303] is configured to extract a domain information
15 associated with the target SIP request based on the one or more target SIP data
fields. It is to be noted that the domain information may include but is not limited to a user/subscriber home information from where the user/subscriber belongs.
[0073] The determination unit [304] is configured to determine a target PLMN
20 from the set of plurality of PLMN [300PN] based on the domain information.
[0074] The identification unit [302] is further configured to identify the target HSS [300T] from the set of HSS [300S] associated with the target PLMN.
25 [0075] The transceiver unit [301] is further configured to transmit the target SIP
request to the target HSS [300T] based on identifying the target HSS [300T].
[0076] In an exemplary embodiment of the present disclosure, the target SIP
request is transmitted to the target HSS [300T] via an interface [305] in the network
30 [300N], wherein the target SIP request further comprises a Destination-Realm
Attribute Value Pair (AVP).
21

[0077] Referring to FIG. 4, an exemplary method flow diagram [400] for
transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber
Server (HSS) [300T], in accordance with exemplary implementations of the present
5 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].
10 [0078] At step [404], the method [400] comprises receiving, by a transceiver unit
[301], a set of network data associated with a network [300N]. It is to be noted that the set of network data comprises a set of plurality of public land mobile network (PLMN) [300PN] associated with the network [300N] and a set of HSS [300S] associated with the network [300N]. It is further noted that each PLMN from the
15 set of plurality of PLMN [300PN] is associated with at least one HSS from the set
of HSS [300S].
[0079] In an exemplary embodiment of the present disclosure, the SIP request is at
least one of a register SIP request, an originating SIP request, and a terminating SIP
20 request.
[0080] In an exemplary aspect of the present disclosure, the one or more target SIP data fields associated with the register SIP request comprise at least a username parameter.
25
[0081] At step [406], the method [400] comprises receiving, by the transceiver unit [301], at a System Information Blocks (SIB) [300Ns] in the network [300N], the Session Initiation Protocol (SIP) request. It is to be noted that the SIB [300Ns] are broadcast messages that are sent from gNodeB to the UEs that contain essential
30 information about the ongoing session.
22

[0082] At step [408], the method [400] comprises identifying, by an identification unit [302], at the SIB [300Ns] in the network [300N], a target SIP request based on the SIP request. It is to be noted that the target SIP request comprises one or more target SIP data fields. 5
[0083] In an exemplary aspect of the present disclosure, in the disclosed method
[400], the one or more target SIP data fields associated with the originating SIP
request comprise at least one of a P-Asserted-Identity header and a from header. In
an exemplary aspect of the present disclosure, the one or more target SIP data fields
10 associated with the terminating SIP request comprise at least a Request-URI (R-
URI). In an exemplary aspect of the present disclosure, the P-Asserted-Identity header associated with the originating SIP request is in a predefined format.
[0084] At step [410], the method [400] comprises extracting, by an extraction unit
15 [303], a domain information associated with the target SIP request based on the one
or more target SIP data fields. It is to be noted that the domain information may include but is not limited to a user/subscriber home information from where the user/subscriber belongs.
20 [0085] At step [412], the method [400] comprises determining, by a determination
unit [304], a target PLMN from the set of plurality of PLMN [300PN] based on the domain information.
[0086] At step [414], the method [400] comprises identifying, by the identification
25 unit [302], the target HSS [300T] from the set of HSS [300S] associated with the
target PLMN.
[0087] At step [416], the method [400] comprises transmitting, by the transceiver
unit [301], the target SIP request to the target HSS [300T] based on identifying the
30 target HSS [300T]. In an exemplary aspect of the present disclosure, the target SIP
request is transmitted to the target HSS [300T] via an interface [305] in the network
23

[300N], wherein the target SIP request further comprises a Destination-Realm Attribute Value Pair (AVP).
[0088] Thereafter, the method [400] terminates at step [418]. 5
[0089] FIG. 5 illustrates an exemplary architecture diagram of a system [500] for automatically transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS), in accordance with exemplary embodiments of the present disclosure. Further, the system [500] comprises various components such
10 as a Serving–Call Session Control Function (S-CSF) unit [502], Interrogating-Call
Session Control Function (I-CSCF) unit [501] and plurality of Home Subscriber Server (HSS) unit involved in implementation of the features of the present disclosure. Also, all of the components/ units of the system [500] are assumed to be connected to each other unless otherwise indicated below.
15
[0090] Also, in FIG. 5 only a few units are shown, however, the system [500] may comprise multiple such units or the system [500] may comprise any such numbers of said units, as required to implement the features of the present disclosure. In an implementation of the present disclosure, the system [500] as depicted in figure 5
20 in conjunction with system [300] as depicted in figure 3 and method [400] as
depicted in figure 4 is configured to perform in other words as follows:
- In order to efficiently select the Home Subscriber Server (HSS) unit, the
system [300] in conjugation with system [500] is configured to receive, a
preconfigured circle of HSS and HSS information.
25 - The I-CSCF unit [501] and the S-CSCF unit [502] will check if the SIP
request is REGISTER or any other SIP request based on receiving of request.
- The system [500] is configured to determine, for “username” field in
Authorization header, extract the domain information from the “username”
30 field; use extracted domain information to select correct HSS and send the
24

5
10
15

-
-
-

Cx request with Destination-Realm AVP set to user domain based on it is REGISTER request.
The system [500] is configured to determine, if request is originating or terminating request, for other than REGISTER request.
The system [500] is configured to determine, if “P-Asserted-Identity” header is present in SIP URI format, then extract domain information from PAI header field. Else, the system [500] checks “From” header and extract domain information from “From” header field. The system [500] uses extracted domain information to select correct HSS and send the Cx request with Destination-Realm AVP set to user domain based on the request is originating request.
The system [500] is configured to determine, check Request-URI (R-URI) of the request and extract the domain information. The system [500] then uses extracted domain information to select correct HSS and send the Cx request with Destination-Realm AVP set to user domain based on the request is terminating request.

[0091] Referring to FIG. 6 an exemplary method flow chart [600], automatically
transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber
20 Server (HSS), in accordance with exemplary embodiments of the present invention
is shown. In an implementation the method [600] is performed by the system [300] (as depicted in FIG.3) and system [500] (as depicted in Fig. 5).

25
30

[0092] The method [600] is carried out in the following steps:
- Step [602] involves checking of an incoming request.
- Step [604] involves checking of the incoming request being SIP request or any other request. If the request is a register request, then step [604a] is executed. If the request is not the register request, then step [608] is executed.

25

- Step [604a] is executed when a domain information is extracted from a SIP data field such as but not limited to “username”.
- Step [606] involves checking of the request being originating or terminating. If the request is originating at step [608], then step [608a] is executed.
5 However, if the request is not originating, then step [610] is executed which
involves extracting the domain information from “Request-URI (R-URI)”.
Post execution of the step [610], the step [612] is executed where the
selection of the target home subscriber server (HSS) takes place, and the
SIP request is then further transmitted.
10 - In case of the execution of the step [608a], the checking whether a PAI
header field is present in the SIP URI format. If it is present, step [608b] is executed for extraction of the domain information from the PAI header field and eventually the execution of the step [612] takes place.
- However, if the PAI header field is not present in the SIP URI format, then
15 step [608c] takes place with the extraction of the domain information from
the “FROM” header filed in the SIP URI format and eventually the execution of the step [612] takes place.
- Eventually, the method [600] culminates at the step [612] upon the selection
of the HSS.
20
[0093] The present disclosure further discloses a non-transitory computer-readable storage medium storing instruction for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS) [300T], the storage medium comprising executable code which, when executed by one or more units of a
25 system, causes a transceiver unit [301] of the system [300] to receive, a set of
network data associated with a network [300N], wherein the set of network data comprises a set of plurality of public land mobile network (PLMN) [300PN] associated with the network [300N], and a set of HSS [300S] associated with the network [300N], and wherein each PLMN from the set of plurality of PLMN
30 [300PN] is associated with at least one HSS from the set of HSS [300S]. The
instructions further include executable code which, when executed, causes the
26

transceiver unit [301] to receive, at a System Information Blocks (SIB) [300Ns] in
the network [300N], the Session Initiation Protocol (SIP) request. The instructions
further include executable code which, when executed, causes an identification unit
[302] of the system [300] to identify, at the SIB [300Ns] in the network [300N], a
5 target SIP request based on the SIP request, wherein the target SIP request
comprises one or more target SIP data fields. The instructions further include executable code which, when executed, causes an extraction unit [303] of the system [300] to extract, a domain information associated with the target SIP request based on the one or more target SIP data fields. The instructions further include
10 executable code which, when executed, causes a determination unit [304] of the
system [300] to determine, a target PLMN from the set of plurality of PLMN [300PN] based on the domain information. The instructions further include executable code which, when executed, causes the identification unit [302] to further identify, the target HSS [300T] from the set of HSS [300S] associated with
15 the target PLMN; and the transceiver unit [301] to further transmit, the target SIP
request to the target HSS [300T] based on identifying the target HSS [300T].
[0094] Further, in accordance with the present disclosure, it is to be acknowledged that the functionality described for the various the components/units can be
20 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. The functionality of specific units as disclosed in the disclosure should not be construed as limiting the scope of the present disclosure. Consequently, alternative
25 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.
[0095] As is evident from the above, the present disclosure provides a technically
30 advanced solution for transmitting a Session Initiation Protocol (SIP) request to a
target Home Subscriber Server (HSS). The present disclosure provides a technically
27

advanced solution for efficiently selecting a Home Subscriber Server (HSS) by enabling I-CSCF and S-CSCF to serve multiple circles, the invention optimizes the use of IMS (IP Multimedia Subsystem) Core elements. This leads to improved resource utilization and scalability within the network infrastructure. The ability of these network elements to efficiently handle requests from various circles enhances the overall performance and capacity of the IMS Core. This technical effect contributes to a more robust and versatile system, capable of accommodating multiple circles while maintaining high-quality service delivery. Moreover, the present solution showcases a technical advancement by addressing the challenge of multi-circle IMS core deployment. The solution proposed in the invention streamlines the operation of I-CSCF and S-CSCF, enabling seamless connectivity and accurate routing to the appropriate Home Subscriber Server (HSS) for each subscriber. This advancement enhances network management, reduces potential data unavailability issues, and promotes reliable communication within the multi-PLMN environment.
[0096] 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 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.

We Claim:
1. A method [400] for transmitting a Session Initiation Protocol (SIP) request
to a target Home Subscriber Server (HSS) [300T], the method [400]
comprising:
- receiving, by a transceiver unit [301], a set of network data associated with a network [300N], wherein the set of network data comprises a set of plurality of public land mobile network (PLMN) [300PN] associated with the network [300N], and a set of HSS [300S] associated with the network [300N], and wherein each PLMN from the set of plurality of PLMN [300PN] is associated with at least one HSS from the set of HSS [300S];
- receiving, by the transceiver unit [301], at a System Information Block (SIB) [300Ns] in the network [300N], the Session Initiation Protocol (SIP) request;
- identifying, by an identification unit [302], at the SIB [300Ns] in the network [300N], a target SIP request based on the SIP request, wherein the target SIP request comprises one or more target SIP data fields;
- extracting, by an extraction unit [303], a domain information associated with the target SIP request based on the one or more target SIP data fields;
- determining, by a determination unit [304], a target PLMN from the set of plurality of PLMN [300PN] based on the domain information;
- identifying, by the identification unit [302], the target HSS [300T] from the set of HSS [300S] associated with the target PLMN based on the domain information; and
- transmitting, by the transceiver unit [301], the target SIP request to the target HSS [300T] based on identifying the target HSS [300T].
2. The method [400] as claimed in claim 1, wherein the SIP request is at least
one of a register SIP request, an originating SIP request, and a terminating
SIP request.

3. The method [400] as claimed in claim 2, wherein, the one or more target SIP data fields associated with the register SIP request comprise at least a username parameter.
4. The method [400] as claimed in claim 2, wherein, the one or more target SIP data fields associated with the originating SIP request comprise at least one of a P-Asserted-Identity header and a from header.
5. The method [400] as claimed in claim 2, wherein, the one or more target SIP data fields associated with the terminating SIP request comprise at least a Request-URI (R-URI).
6. The method [400] as claimed in claim 4, wherein the P-Asserted-Identity header associated with the originating SIP request is in a predefined format.
7. The method [400] as claimed in claim 1, wherein the target SIP request is transmitted to the target HSS [300T] via an interface [305] in the network [300N], wherein the target SIP request further comprises a Destination-Realm Attribute Value Pair (AVP).
8. A system [300] for transmitting a Session Initiation Protocol (SIP) request to a target Home Subscriber Server (HSS) [300T], the system [300] comprising:
- a transceiver unit [301], wherein the transceiver unit [301] is configured to:
• receive, a set of network data associated with a network [300N], wherein the set of network data comprises a set of plurality of public land mobile network (PLMN) [300PN] associated with the network [300N], and a set of HSS [300S] associated with the network [300N], and wherein each PLMN from the set of plurality of PLMN [300PN] is associated with at least one HSS from the set of HSS [300S];
• receive, at a System Information Blocks (SIB) [300Ns] in the network [300N], the Session Initiation Protocol (SIP) request;

- an identification unit [302], connected to at least the transceiver unit [301], wherein the identification unit [302] is configured to identify, at the SIB [300Ns] in the network [300N], a target SIP request based on the SIP request, wherein the target SIP request comprises one or more target SIP data fields;
- an extraction unit [303], connected to at least the identification unit [302], the extraction unit [303] configured to extract, a domain information associated with the target SIP request based on the one or more target SIP data fields;
- a determination unit [304], connected to at least the extraction unit [303], the determination unit [304] configured to determine, a target PLMN from the set of plurality of PLMN [300PN] based on the domain information, and
wherein the identification unit [302] is further configured to identify, the target HSS [300T] from the set of HSS [300S] associated with the target PLMN; and
wherein the transceiver unit [301] is further configured to transmit, the target SIP request to the target HSS [300T] based on identifying the target HSS [300T].
9. The system [300] as claimed in claim 8, wherein, the SIP request is at least one of a register SIP request, an originating SIP request, and a terminating SIP request.
10. The system [300] as claimed in claim 9, wherein, the one or more target SIP data fields associated with the register SIP request comprise at least a username parameter.
11. The system [300] as claimed in claim 9, wherein, the one or more target SIP data fields associated with the originating SIP request comprise at least one of a P-Asserted-Identity header and a from header.

12. The system [300] as claimed in claim 9, wherein, the one or more target SIP data fields associated with the terminating SIP request comprise at least a Request-URI (R-URI).
13. The system [300] as claimed in claim 11, wherein the P-Asserted-Identity header associated with the originating SIP request is in a predefined format.
14. The system [300] as claimed in claim 8, wherein the target SIP request is transmitted to the target HSS [300T] via an interface [305] in the network [300N], wherein the target SIP request further comprises a Destination-Realm Attribute Value Pair (AVP).