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 MANAGING A GRACEFUL
SHUTDOWN OF A CONVERGED TELEPHONY
APPLICATION 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 MANAGING A GRACEFUL SHUTDOWN OF A CONVERGED TELEPHONY APPLICATION SERVER
FIELD OF INVENTION
[0001] Embodiments of the present disclosure generally relate to network
performance management systems. More particularly, embodiments of the present disclosure relate to managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event.
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] An IP Multimedia Subsystem, IMS for short, refers to the standard
for a telecommunication system which controls multimedia services accessing different networks. It is predominantly used for delivering interactive services like Voice, IP Centrex Service, Video chat, Video Conferencing, and Instant Messaging-based multimedia services. A Serving Call Session Control Function (SCSCF) is a primary node in the IMS and responsible for conducting both registration and session control for the registered UEs. It functions as a registrar and enables the network location information of the UEs to be available at the HSS. In IMS, against an Initial Filter Criteria (IFC), application servers are defined in SCSCF to provide enriched voice related services. The IFC is installed in the SCSCF during registration process. The IFC contains parameters to filter the next action. When the parameters are identified in a message, the SCSCF can use the IFC to determine the next action efficiently. The SCSCF selects Converged Telephony Application Server (CTAS) application server, which provides Multimedia Telephony (MMTel) supplementary services, such as Online Charging, Ringback Tone (RBT), Call Forwarding, Conference, Call Hold, Call Waiting etc. As mentioned above, the CTAS maintains all session related information till the call ends while staying in the signaling path of any VoLTE or VoNR (Voice over New Radio) call establishment procedure. Once the call is completed, the CTAS writes down call data records pertaining to that call.
[0005] Typically, maintenance and software update of any application is
achieved by restarting the application. Voice services, video services, text services, and the like, on IMS network are managed by a Converged Telephony Application Server (CTAS). The CTAS may also provide call services like voicemail, call forwarding, session controlling services, and the like. The CTAS on IMS network, while staying in the signaling path of any VoLTE or VoNR (Voice over New Radio) call establishment procedure, maintains all session related information till

the call ends. In some cases, the call can last till 3 hours. When the call is completed, the CTAS records call data records pertaining to that call, which is a necessary regulatory mandate. Hence, any planned event requires more than a 3-hour window, which acts as a blocker for faster roll out of any critical features and updates. Further, maintenance engineers are also faced with unnecessary operational overheads of removing and adding application servers in active pool members.
[0006] Any product requires regular maintenance and to enhance customer
experience, new features are also introduced regularly. Same is the case with the CTAS application. To do so, a software upgrade is required and that is followed by an application restart.
[0007] Further, over the period of time various solutions have been
developed to provide shutdown solutions for planned maintenance of applications. However, there are certain challenges with existing solutions.
[0008] Since CTAS maintains session and revenue related information,
application restart cannot be performed abruptly. Moreover, it is also imperative to not select CTAS instance, which is under maintenance, for further call routing during the maintenance window. Also, importantly, since a call session can last for 3 hours, the Maintenance Operation Protocol (MOP) execution procedure kicks in almost 3 hours prior to the actual application upgrade. This is because the CTAS instance needs to be removed from the pool of application servers defined in the SCSCF. Then, the CTAS being the authoritative entity of maintaining timer for maximum call duration, can terminate all anchored sessions including the longer ones.
[0009] Furthermore, the workload of maintenance engineers is phenomenal
for many reasons, including but not limited to, the rising planned event windows.
[0010] Thus, there exists an imperative need in the art for providing
solutions for graceful shutdown of applications for planned maintenance so that

faster rollout of features, particularly, important and critical features, can be done, which the present disclosure aims to address.
SUMMARY
[0011] 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.
[0012] An aspect of the present disclosure may relate to a method for
managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event. The method includes receiving a set of service unavailable response for one or more calling requests, at a transceiver unit at a Serving Call Session Control Function (SCSCF) module from a Converged Telephony Application Server (CTAS) instance implementing the CTAS application. The method further encompasses blacklisting, by a CTAS manager at the SCSCF module, the CTAS instance based at least on the received set of service unavailable response. Furthermore, the method includes removing, by the CTAS manager at the SCSCF module, the CTAS instance from an active pool of one or more CTAS instances stored at a storage unit at the SCSCF module. Furthermore, the method includes transmitting, by the transceiver unit at the SCSCF module to the CTAS instance, a periodic health check query. The method further includes receiving, by the transceiver unit at the SCSCF module from the CTAS instance, a response for the periodic health check query, wherein the response is one of a positive response and a negative response. Further, the method includes adding, by the CTAS manager at the SCSCF module, the CTAS instance in the active pool of one or more CTAS instances, in an event the positive response is received.
[0013] In an exemplary aspect of the present disclosure, the adding, by the
CTAS manager at the SCSCF module, the CTAS instance in the active pool of one

or more CTAS instances facilitates acceptance of one or more new calling requests at the CTAS instance.
[0014] In an exemplary aspect of the present disclosure, the blacklisting of
the CTAS instance is further based on an event where a number of service unavailable responses in the set of service unavailable response is more than a pre-defined threshold.
[0015] In an exemplary aspect of the present disclosure, the set of service
unavailable response is received at the transceiver unit at the SCSCF module after executing the graceful shutdown command received from a command line interface and shutting down gracefully one or more ongoing sessions associated with the CTAS instance.
[0016] In an exemplary aspect of the present disclosure, the event is a
planned event.
[0017] Another aspect of the present disclosure may relate to a system for
managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event. The system comprises a Serving Call Session Control Function (SCSCF) module. The SCSCF module further comprises a transceiver unit configured to receive from a Converged Telephony Application Server (CTAS) instance implementing the CTAS application, a set of service unavailable response for one or more calling requests. The SCSCF module further comprises a CTAS manager connected to at least the transceiver unit. The CTAS manager is configured to blacklist the CTAS instance based at least on the received set of service unavailable response. The CTAS manager is further configured to remove the CTAS instance from an active pool of one or more CTAS instances stored at a storage unit at the SCSCF module. The transceiver unit is further configured to transmit, to the CTAS instance, a periodic health check query. The transceiver unit is further configured to receive, from the CTAS instance, a response for the periodic health check query, wherein the response is one of a positive response and

a negative response. The CTAS manager is further configured to add the CTAS instance in the active pool of one or more CTAS instances, in an event the positive response is received.
5 [0018] Yet another aspect of the present disclosure may relate to a non-
transitory computer readable storage medium storing instructions for managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event, 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, from a
10 Converged Telephony Application Server (CTAS) instance implementing the
CTAS application, a set of service unavailable response for one or more calling requests. Further, the instructions include executable code which, when executed by one or more units of a system, causes a CTAS manager of the system to blacklist the CTAS instance based at least on the received set of service unavailable
15 response. Further, the instructions include executable code which, when executed
by one or more units of a system, causes the CTAS manager of the system to remove the CTAS instance from an active pool of one or more CTAS instances stored at a storage unit at the SCSCF module. Further, the instructions include executable code which, when executed by one or more units of a system, causes
20 the transceiver unit of the system to transmit a periodic health check query to the
CTAS instance. Further, the instructions include executable code which, when executed by one or more units of a system, causes the transceiver unit of the system to receive a response for the periodic health check query from the CTAS instance.
25 OBJECTS OF THE INVENTION
[0019] Some of the objects of the present disclosure, which at least one
embodiment disclosed herein satisfies are listed herein below.
30 [0020] It is an object of the present disclosure to provide a system and a
method for graceful shutdown of an application for planned maintenance.
7

[0021] It is another object of the present disclosure to ensure faster rollout
of important and critical features.
5 [0022] It is yet another object of the present disclosure to provide a solution
in which the system can be brought to maintenance state immediately without waiting for 3-hour time.
[0023] It is yet another object of the present disclosure to provide a solution
10 that minimizes planned event window and reduces workload on maintenance
engineers.
[0024] It is yet another object of the present disclosure to provide a solution
that eliminates unnecessary operational overheads of removing and adding
15 application servers in active pool members.
[0025] It is yet another object of the present disclosure to provide a solution
that is an improvement over standard procedure followed across telecom nodes.
20 [0026] It is yet another object of the present disclosure to bring the down
the time of maintenance window significantly and helping in adding new features across the vast network rapidly.
DESCRIPTION OF THE DRAWINGS
25
[0027] 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
30 necessarily to scale, emphasis instead being placed upon clearly illustrating the
principles of the present disclosure. Also, the embodiments shown in the figures
8

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
5 circuitry commonly used to implement such components.
[0028] FIG. 1 illustrates an exemplary block diagram representation of 5th
generation core (5GC) network architecture.
10 [0029] 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.
[0030] FIG. 3 illustrates an exemplary block diagram of a system for
15 managing a graceful shutdown of a Converged Telephony Application Server
(CTAS) for an event, in accordance with exemplary implementations of the present disclosure.
[0031] FIG. 4 illustrates an exemplary implementation of the system for
20 managing a graceful shutdown of a Converged Telephony Application Server
(CTAS) for an event, in accordance with exemplary implementations of the present disclosure.
[0032] FIG. 5 illustrates a method flow diagram for managing a graceful
25 shutdown of a Converged Telephony Application Server (CTAS) for an event, in
accordance with exemplary implementations of the present disclosure.
[0033] FIG. 6 illustrates an exemplary implementation of the method flow
30 managing a graceful shutdown of a Converged Telephony Application Server
9

(CTAS) for an event, in accordance with exemplary implementations of the present disclosure.
[0034] The foregoing shall be more apparent from the following more
5 detailed description of the disclosure.
DETAILED DESCRIPTION
[0035] In the following description, for the purposes of explanation, various
10 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 combination of other features. An individual feature may
15 not address any of the problems discussed above or might address only some of
the problems discussed above.
[0036] The ensuing description provides exemplary embodiments only, and
is not intended to limit the scope, applicability, or configuration of the disclosure.
20 Rather, the ensuing description of the exemplary embodiments will provide those
skilled in the art with an enabling description for implementing an exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the disclosure as set forth.
25
[0037] 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
30 may be shown as components in block diagram form in order not to obscure the
embodiments in unnecessary detail.
10

[0038] 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
5 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.
10 [0039] 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 necessarily to be construed as preferred or advantageous over other aspects or
15 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
20 precluding any additional or other elements.
[0040] 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
25 processor, a special 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
30 perform signal coding data processing, input/output processing, and/or any other
functionality that enables the working of the system according to the present
11

disclosure. More specifically, the processor or processing unit is a hardware processor.
[0041] As used herein, “a user equipment”, “a user device”, “a smart-user-
5 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 user equipment/device may include, but is not limited to, a mobile
10 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
15 and any other such unit(s) which are required to implement the features of the
present disclosure.
[0042] As used herein, “storage unit” or “memory unit” refers to a machine
or computer-readable medium including any mechanism for storing information
20 in a form readable by a computer or similar machine. For example, a computer-
readable medium includes read-only memory (“ROM”), random 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
25 their respective functions.
[0043] 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
30 that define communication or interaction of one or more modules or one or more
12

units with each other, which also includes the methods, functions, or procedures that may be called.
[0044] All modules, units, components used herein, unless explicitly
5 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, one or
more microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASIC), Field
10 Programmable Gate Array circuits (FPGA), any other type of integrated circuits,
etc.
[0045] As used herein the transceiver unit includes at least one receiver and
at least one transmitter configured respectively for receiving and transmitting data,
15 signals, information or a combination thereof between units/components within
the system and/or connected with the system.
[0046] As discussed in the background section, the current known solutions
have several shortcomings. The present disclosure aims to overcome the above-
20 mentioned and other existing problems in this field of technology by providing
method and system of managing a graceful shutdown of a Converged Telephony
Application Server (CTAS) for an event.
[0047] FIG. 1 illustrates an exemplary block diagram representation of 5th
25 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 network
(RAN) [104], an access and mobility management function (AMF) [106], a
Session Management Function (SMF) [108], a Service Communication Proxy
30 (SCP) [110], an Authentication Server Function (AUSF) [112], a Network Slice
Specific Authentication and Authorization Function (NSSAAF) [114], a Network
13

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 User Plane Function (UPF) [128], a data network (DN) [130],
5 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.
[0048] Radio Access Network (RAN) [104] is the part of a mobile
10 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 [0049] 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 [0050] 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) for data forwarding and handles IP address allocation and QoS enforcement.
25 [0051] 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.
14

[0052] Authentication Server Function (AUSF) [112] is a network function
in the 5G core responsible for authenticating UEs during registration and providing security services. It generates and verifies authentication vectors and tokens.
5 [0053] Network Slice Specific Authentication and Authorization Function
(NSSAAF) [114] is a network function that provides authentication and authorization services specific to network slices. It ensures that UEs can access only the slices for which they are authorized.
10 [0054] 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.
[0055] Network Exposure Function (NEF) [118] is a network function that
15 exposes capabilities and services of the 5G network to external applications,
enabling integration with third-party services and applications.
[0056] Network Repository Function (NRF) [120] is a network function
that acts as a central repository for information about available network functions
20 and services. It facilitates the discovery and dynamic registration of network
functions.
[0057] Policy Control Function (PCF) [122] is a network function
responsible for policy control decisions, such as QoS, charging, and access control,
25 based on subscriber information and network policies.
[0058] Unified Data Management (UDM) [124] is a network function that
centralizes the management of subscriber data, including authentication, authorization, and subscription information. 30
15

[0059] Application Function (AF) [126] is a network function that
represents external applications interfacing with the 5G core network to access network capabilities and services.
5 [0060] User Plane Function (UPF) [128] is a network function responsible
for handling user data traffic, including packet routing, forwarding, and QoS enforcement.
[0061] Data Network (DN) [130] refers to a network that provides data
10 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.
[0062] FIG. 2 illustrates an exemplary block diagram of a computing
15 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 establishing packet data unit (PDU) session with user plane function
(UPF) utilising the system. In another implementation, the computing device [200]
20 itself implements the method for establishing packet data unit (PDU) session with
user plane function (UPF) using one or more units configured within the computing device [200], wherein said one or more units are capable of implementing the features as disclosed in the present disclosure.
25 [0063] 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-
30 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
16

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-
5 purpose machine 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].
10 [0064] A storage device [210], such as a magnetic disk, optical disk, or
solid-state 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 display [212], such as a cathode ray tube (CRT), Liquid crystal Display (LCD), Light Emitting Diode (LED) display, Organic LED (OLED) display, etc. for
15 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 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
20 direction information and command selections to the processor [204], and for
controlling cursor movement on the display [212]. The 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 [0065] 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
30 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
17

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
5 of the present disclosure, hard-wired circuitry may be used in place of or in
combination with software instructions.
[0066] The computing device [200] also may include a communication
interface [218] coupled to the bus [202]. The communication interface [218]
10 provides a two-way data communication coupling to a network link [220] that is
connected to a local network [222]. For example, the communication interface [218] may be an integrated 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
15 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 optical signals that carry digital data streams representing various types of information.
20
[0067] 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 [228],
25 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, and/or stored in the storage device [210], or other non-volatile storage for later execution.
30 [0068] The present disclosure is implemented by a system [300] as shown
in FIG. 3. In an implementation, the system [300] may include the computing
18

device [200] (as shown in FIG. 2). It is further noted that the computing device [200] is able to perform the steps of a method [500] (as shown in FIG. 5).
[0069] Referring to FIG. 3, an exemplary block diagram of a system [300]
5 for managing a graceful shutdown of a Converged Telephony Application Server
(CTAS) for an event, is shown, in accordance with the exemplary implementations of the present disclosure. The system [300] comprises one Serving Call Session Control Function (SCSCF) module [302]. The SCSCF module [302] comprises at least one transceiver unit [304], at least one CTAS manager [306] and at least one
10 storage unit [308]. 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 FIG. 3, all units shown within the system should also be assumed to be connected to each other. Further, the system [300] is intended to be read in conjunction with an exemplary implementation system [400] as shown in FIG. 4.
15 The systems in FIG. 3 and FIG. 4 complement each other.
[0070] 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
20 disclosure. The system [300] may be a part of the user device / or may be
independent of but in communication with the user device (may also referred herein as a UE). In another implementation, the system [300] may reside in a server or a network entity. In yet another implementation, the system [300] may reside partly in the server/ network entity and partly in the user device.
25
[0071] The system [300] is configured for managing a graceful shutdown
of a Converged Telephony Application Server (CTAS) application for an event, with the help of the interconnection between the components/units of the system [300]. The event of graceful shutdown of the CTAS application is a planned event.
30 A graceful shutdown of a CTAS application can be described as a process when
the CTAS application, before shutting down, deletes all active call sessions and
19

reports the current usage to the online charging function (OCS) [412] as shown in
FIG. 4. This ensures there is no revenue loss, and all usage is correctly reported.
Alternatively, if the CTAS application does not follow a graceful shutdown
process, and shuts down abruptly, then all the ongoing connected call sessions will
5 not be deleted and hence there will be no usage reporting, which will result in
revenue loss. Therefore, graceful shutdown provides an improved solution over standard procedures followed across telecom nodes.
[0072] The system [300] shows a Serving Call Session Control Function
10 (SCSCF) module [302]. In an Internet Protocol Multimedia Subsystem (IMS), the
SCSCF module [302] is a central node to control call sessions and communication between a user and different networks. The SCSCF module [302] is responsible for policy enforcement in a session, making decisions for service instances. The SCSCF module [302] further comprises a transceiver unit [304] configured to
15 receive a set of service unavailable response for one or more calling requests, from
a Converged Telephony Application Server (CTAS) instance [402] implementing the CTAS application. The CTAS application is the Converged Telephony Application Server (TAS) which can be deployed as Voice over Long-Term Evolution (VoLTE), Telephony Application Server (TAS) as well as Business
20 TAS. VoLTE TAS, also known as Multimedia Telephony (MMTel-TAS), is a
component used in the core network of a telecom operator to provide telephony applications and additional multimedia functions. The CTAS instance [402] running the CTAS application, provides services which includes but may not be limited to Ringback Tone (RBT), call forwarding, conference call, call hold, call
25 waiting. RBT refers to ring back tone that is an audible indication heard by the
calling party while waiting for their call to be answered by the called party. The CTAS instance [402] may stay in the signalling path of any call establishment procedure and maintain session related information till call ends. The CTAS instance [402] may store the call data records pertaining to the call.
30
20

[0073] The SCSCF module [302] in the system [300], further comprises a
CTAS manager [306] connected to at least the transceiver unit [304]. In an
implementation of the present disclosure, the CTAS manager [306] may identify
the CTAS instance [402] for which the planned event is going to be performed.
5 The planned event may be a planned maintenance event which are carried out
before a new release. The maintenance engineers identify the number of CTAS instances in a telecom circle and plan the maintenance event one by one for all the instances. The maintenance engineer identifies the CTAS instance for which the planned event is to be performed and accordingly the CTAS manager [306]
10 initiates the graceful shutdown command. In another implementation of the present
disclosure, the CTAS manager [306] may execute the graceful shutdown command by using the command line interface to bring the system into a ‘Maintenance’ state. Upon execution of the graceful shutdown command, the CTAS application running on the CTAS instance [402] will end all active sessions and write down
15 corresponding call data records. Any new calling request will be rejected with a
service unavailable response. The CTAS manager [306] initiates termination of all established sessions gracefully by executing the graceful shutdown command.
[0074] In an implementation of the present disclosure, the transceiver unit
20 [304] at the SCSCF module [302] may send a 503-service unavailable response to
reject a new call request. The CTAS manager [306] is configured to blacklist the
CTAS instance [402] based at least on the received set of service unavailable
response. The CTAS manager [306] is further configured to remove the CTAS
instance [402] from an active pool of one or more CTAS instances stored at a
25 storage unit [308] at the SCSCF module [302]. In this way, the CTAS instance
[402] can be brought to the ‘maintenance’ state immediately without waiting for
long time. The blacklisting the CTAS instance [402] refers to a state when the
CTAS instance [402] will not be reachable or will be in an out of service state. The
CTAS instance [402] after blacklisting will be removed from the active pool of
30 CTAS instances, ensuring that the blacklisted CTAS instance [402] is not available
for any service.
21

[0075] The CTAS manager [306] is configured to blacklist the CTAS
instance [402] based on an event where a number of service unavailable responses
in the set of service unavailable response is more than a pre-defined threshold. In
5 an implementation of the present disclosure, the pre-defined threshold may be
defined by a user. In an exemplary implementation, the pre-defined threshold is
defined as 30 attempts by a user to connect in a second. In an implementation of
the present disclosure, the active pool refers to a pool or group of the CTAS
instances, that may be providing services and performing the requests actively.
10
[0076] The storage unit [308] of the SCSCF module [302] is a database to
store the active pool of the one or more CTAS instances. The storage unit [308] of
the SCSCF module [302] may be updated on the basis of an update in the active
pool of the one or more CTAS instances in the SCSCF module [302].
15
[0077] The transceiver unit [304] at the SCSCF module [302] is further
configured to transmit to the CTAS instance [402], a periodic health check query.
The transceiver unit [304] at the SCSCF module [302] is further configured to
receive, from the CTAS instance [402], a response for the periodic health check
20 query. The response is one of a positive response and a negative response. The
positive response of the periodic health check query refers to the planned event being completed on the CTAS instance [402]. The negative response of the periodic health check refers to the planned event being under process on the CTAS instance [402]. In an exemplary implementation, the SCSCF module [302] runs a
25 blacklist timer for a defined period of time and at the expiry of the blacklist timer,
checks for a registration request to the blacklisted CTAS instance [402]. In an exemplary implementation, the blacklist timer may be run periodically for five minutes.
30 [0078] The CTAS manager [306] is further configured to add the CTAS
instance [402] in the active pool of one or more CTAS instances, in an event the positive response is received. The CTAS manager [306] is configured to add the
22

CTAS instance [402] in the active pool of one or more CTAS instances to facilitate
acceptance of one or more new calling requests at the CTAS instance [402]. In an
exemplary implementation, if the CTAS instance [402] responds to the registration
request sent by the SCSCF module [302], then the CTAS instance [402] is added
5 back to the active pool of CTAS instances and becomes available for handling call
requests.
[0079] The system [300] will be clear through an exemplary
implementation of the system [400] as shown in FIG. 4. Referring to FIG. 4, it
10 illustrates an exemplary implementation for managing a graceful shutdown of a
Converged Telephony Application Server (CTAS) for an event, in accordance with exemplary implementations of the present disclosure. Further, the exemplary implementation [400] is intended to be read in conjunction with the system [300] as shown in FIG. 3. The systems in FIG. 3 and FIG. 4 complement each other.
15
[0080] Further, in accordance with the present disclosure, it is to be
acknowledged that the functionality described for the various components/units can be implemented interchangeably. While specific embodiments may disclose a particular functionality of these units for clarity, it is recognized that various
20 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 arrangements and substitutions of units, provided they achieve the intended functionality described herein, are considered to be encompassed within the scope
25 of the present disclosure.
[0081] The system [400] as shown in FIG. 4 comprises a plurality of
components. For example and by no way limiting the scope of the present
disclosure, the system [400] comprises the Converged Telephony Application
30 Server (CTAS) instance [402], a mobile number portability (MNP) [404], a
network authentication function (NAF) [406], the serving call session control function instance (SCSCF module) [302], a diameter routing agent (DRA) [408],
23

a caller ring back tone (CRBT) [414], a multimedia resource function (MRF) [416], a home subscriber server (HSS) [410] and an online charging system (OCS) [412].
5 [0082] As shown in FIG. 4, the CTAS instance [402] is communicably
connected to the mobile number portability (MNP) [404], the network authentication function (NAF) [406], the serving call session control function (SCSCF) module [302], the diameter routing agent (DRA) [408], the caller ring back tone (CRBT) [414] and the multimedia resource function (MRF) [416]. The
10 CTAS instance [402] runs a CTAS application. The CRBT [414] service
empowers subscribers/users to redefine the calling experience by replacing standard ring-back tones with customized audio content, creating a unique and engaging personalised calling experience. The MRF [416] in conjunction with the SCSCF module [302] is responsible for carrying out a variety of processing tasks
15 on media streams associated with particular services. The DRA [408] provides
routing capabilities to ensure that messages are routed among the correct elements in the IMS network. The DRA [408] is connected with Home Subscriber Server (HSS [410]) and Online charging system (OCS [412]). The SCSCF module [302] uses DRA [408] for access to the HSS [410] and OCS [412]. Home Subscriber
20 Server (HSS) [410] is the main subscriber database used within the IP Multimedia
Subsystem (IMS) which provides details of the subscribers/users to other entities within the network. The OCS [412] is a system allowing a communications service provider to charge their customers, in real time, based on service usage.
25 [0083] For performing graceful shutdown of the CTAS instance [402] for
the planned event, the graceful shutdown command may be received from a command line interface for execution. The SCSCF module [302] may be configured to shut down gracefully one or more ongoing sessions associated with the CTAS instance [402]. The SCSCF module [302] may be configured to log a
30 set of data records information related to the shut-down sessions. The CTAS
application running on the CTAS instance [402] may be configured to reject the new call requests by sending a 503-service unavailable response. On receiving the
24

503-service unavailable responses, and when the 503-service unavailable
responses breach the pre-defined threshold defined by the user, the SCSCF module
[302] may immediately blacklist the CTAS instance [402] and remove the CTAS
instance [402] from the active pool of CTAS instances. The SCSCF module [302]
5 is further configured to execute the maintenance operation protocol (MOP) for the
planned event. The MOP for the planned event includes restarting the CTAS instance [402] and sending the periodic health check query from the SCSCF module [302] to the CTAS instance [402]. The response received from the CTAS instance [402] can be one of a positive response and a negative response. The
10 positive response of the periodic health check query refers to the planned event
being completed on the CTAS instance [402]. The negative response of the periodic health check refers to the planned event being under process on the CTAS instance [402]. Further, the SCSCF module [302] is configured to add the CTAS instance [402] instance in an active pool of one or more CTAS instances in an
15 event when the positive response is received by the SCSCF module [302]. Also,
the CTAS instance [402] is configured to start accepting one or more new calling requests.
[0084] In a preferred embodiment of the invention, once the maintenance
20 engineer identifies the CTAS instance [402] for which the planned event is
requested, the graceful shutdown command is executed by using the command line interface, thereby bringing the system into “Maintenance” state. check query from the SCSCF module [302].
25 [0085] Referring to FIG. 5, an exemplary method flow diagram [500] for
managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event, in accordance with exemplary implementations of the present disclosure is shown. In an implementation the method [500] is performed by the system [300]. Further, the method [500] is intended to be read in conjunction with
30 the exemplary implementation system [400] as shown in FIG. 4. The methods and
25

systems in FIG. 4 and FIG. 5 complement each other. Also, as shown in FIG. 5, the method [500] starts at step [502].
[0086] At step [504], the method comprises receiving, at a transceiver unit
5 [304] at a Serving Call Session Control Function (SCSCF) module [302] from a
Converged Telephony Application Server (CTAS) instance [402] implementing the CTAS application, a set of service unavailable response for one or more calling requests. The set of service unavailable response is received at the transceiver unit [304] at the SCSCF module [302] after executing the graceful shutdown command
10 received from a command line interface and shutting down gracefully one or more
ongoing sessions associated with the CTAS instance [402]. The event is a planned event. A graceful shutdown of a CTAS application can be described as a process when the CTAS application, before shutting down, deletes all active call sessions and reports the current usage to the online charging function (OCS) [412] as shown
15 in FIG. 4. This ensures there is no revenue loss, and all usage is correctly reported.
Alternatively, if the CTAS application does not follow a graceful shutdown process, and shuts down abruptly, then all the ongoing connected call sessions will not be deleted and hence there will be no usage reporting, which will result in revenue loss. Therefore, graceful shutdown provides an improved solution over
20 standard procedures followed across telecom nodes. In an implementation of the
present disclosure, a CTAS manager [306] at the SCSCF module [302] may identify the CTAS instance [402] for which the planned event is going to be performed. In another implementation of the present disclosure, the CTAS manager [306] may execute the graceful shutdown command by using the
25 command line interface to bring the system into the ‘Maintenance’ state. The
CTAS manager [306] may reject a new call request by sending the 503-service unavailable response.
[0087] Next at step [506], the method comprises blacklisting, by the CTAS
30 manager [306] at the SCSCF module [302], the CTAS instance [402] based at least
on the received set of service unavailable response. The blacklisting of the CTAS
instance [402] is further based on an event where a number of service unavailable
26

responses in the set of service unavailable response is more than a pre-defined
threshold. In an implementation of the present disclosure, the pre-defined
threshold may be defined by a user. In an exemplary implementation, the pre¬
defined threshold is defined as 30 attempts by a user to connect in a second. In an
5 implementation of the present disclosure, the blacklisting is performed by the
CTAS manager [306] immediately, upon receiving the 503-service unavailable
response, where the 503-service unavailable response breaches the pre-defined
threshold. The blacklisting the CTAS instance [402] refers to a state when the
CTAS instance [402] will not be reachable or will be in an out of service state. The
10 CTAS instance [402] after blacklisting will be removed from the active pool of
CTAS instances, ensuring that the blacklisted CTAS instance [402] is not available for any service.
15 [0088] Next at step [508], the method comprises removing, by the CTAS
manager [306] at the SCSCF module [302], the CTAS instance [402] from an active pool of one or more CTAS instances stored at a storage unit [308] at the SCSCF module [302]. In an implementation of the present disclosure, the active pool refers to a pool or group of the CTAS instances, that may be providing
20 services and performing the requests actively.
[0089] Next, at step [510], the method comprises transmitting, by the
transceiver unit [304] at the SCSCF module [302] to the CTAS instance [402], a
periodic health check query. In an implementation of the present disclosure, the
25 CTAS manager [306] may perform the periodic health check query. In an
exemplary implementation, the SCSCF module [302] runs a blacklist timer for a
defined period of time and at the expiry of the blacklist timer, checks for a
registration request to the blacklisted CTAS instance [402]. In an exemplary
implementation, the blacklist timer may be run periodically for five minutes.
30
[0090] Next, at step [512], the method encompasses receiving, by the
transceiver unit [304] at the SCSCF module [302] from the CTAS instance [402],
27

a response for the periodic health check query. The response is one of a positive
response and a negative response. The positive response of the periodic health
check query refers to the planned event being completed in the CTAS instance
[402]. The negative response of the periodic health check refers to the planned
5 event being under process.
[0091] Next, at step [514], the method comprises adding, by the CTAS
manager [306] at the SCSCF module [302], the CTAS instance [402] in the active pool of one or more CTAS instances, in an event the positive response is received.
10 The adding, by the CTAS manager [306] at the SCSCF module [302], the CTAS
instance [402] in the active pool of one or more CTAS instances facilitates acceptance of one or more new calling requests at the CTAS instance [402]. In an exemplary implementation, if the CTAS instance [402] responds to the registration request sent by the SCSCF module [302], then the CTAS instance [402] is added
15 back to the active pool of CTAS instances and becomes available for handling call
requests.
[0092] Thereafter, the method terminates at step [516].
20
[0093] FIG. 6 illustrates an exemplary implementation of the method flow
for managing a graceful shutdown of a Converged Telephony Application Server
(CTAS) for an event, in accordance with exemplary implementations of the present
disclosure.
25
[0094] The method may begin at step [602], where the set of service
unavailable response for the one or more calling requests are obtained at the
SCSCF module [302].
30 [0095] At step [604], the method includes identifying, by the SCSCF
module [302], the CTAS instance [402] for which the planned event is requested.
28

[0096] At step [606], the SCSCF module [302] may execute the graceful
shutdown command by using a command line interface to bring the system into “Maintenance” state.
5 [0097] At step [608], the SCSCF module [302] may terminate all
established sessions gracefully.
[0098] Next, at step [610], the SCSCF module [302] may reject a new call
request with a 503-service unavailable response. The 503-response may be sent for
10 each new calling request.
[0099] Next, at step [612], the method [600] may comprise blacklisting the
CTAS instance [402] by the SCSCF module [302], upon receiving the 503-service
unavailable response. The SCSCF module [302] may further remove the CTAS
15 instance [402] from active pool. The CTAS instance [402] may be brought to
maintenance state immediately without waiting for hours.
[0100] Next, at step [614], the SCSCF module [302] may execute the
Maintenance Operation Protocol (MOP) approved for the planned event. The MOP
20 includes but may not be limited to restarting the CTAS instance [402], and sending,
by the SCSCF module [302], a positive acknowledgement for periodic health check query sent to the CTAS instance [402]. The MOP further may include adding the CTAS instance [402] in the active pool by the SCSCF module [302] and resuming the traffic on the server.
25
[0101] The present disclosure further discloses a non-transitory computer
readable storage medium storing instructions for managing a graceful shutdown of a Converged Telephony Application Server (CTAS) for an event, the instructions include executable code which, when executed by one or more units of a system,
30 causes: a transceiver unit [304] at a Serving Call Session Control Function
(SCSCF) module [302] to receive, from a Converged Telephony Application
29

Server (CTAS) instance implementing the CTAS application, a set of service
unavailable response for one or more calling requests; a CTAS manager [306] at
the (SCSCF) module [302] to blacklist the CTAS instance [402] based at least on
the received set of service unavailable response; the CTAS manager [306] to
5 remove the CTAS instance [402] from an active pool of one or more CTAS
instances stored at a storage unit at the SCSCF module [302]; the transceiver unit [304] at the (SCSCF) module [302] to transmit a periodic health check query to the CTAS instance [402]; and the transceiver unit [304] to receive a response for the periodic health check query from the CTAS instance [402].
10
[0102] As is evident from the above, the present disclosure provides a
technically advanced solution for providing graceful shutdown of an application for planned maintenance so that faster rollout of critical features can be performed. The present disclosure ensures that the system can be brought to maintenance state
15 immediately without waiting for 3 hours’ time. Further, the system and method
according to the present disclosure minimize the planned event window and hence, does not act as a blocker for faster rolling out of any critical feature. Furthermore, the system and method according to the present disclosure reduce workload on maintenance engineers as the maintenance engineers get rid of unnecessary
20 operational overheads of removing and adding application servers in active pool
members. Moreover, the present disclosure provides an improvement over
standard procedure followed across telecom nodes. Additionally, the present
system and method bring down the time of maintenance window significantly and
thereby help in adding new features across vast network rapidly.
25
[0103] 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
30 the implementations of the present disclosure will be apparent to those skilled in
30

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 [500] for managing a graceful shutdown of a Converged
Telephony Application Server (CTAS) application for an event, the method
comprising:
- receiving, at a transceiver unit [304] at a Serving Call Session Control Function (SCSCF) module [302] from a Converged Telephony Application Server (CTAS) instance [402] implementing the CTAS application, a set of service unavailable response for one or more calling requests;
- blacklisting, by a CTAS manager [306] at the SCSCF module [302], the CTAS instance [402] based at least on the received set of service unavailable response;
- removing, by the CTAS manager [306] at the SCSCF module [302], the CTAS instance [402] from an active pool of one or more CTAS instances stored at a storage unit [308] at the SCSCF module [302];
- transmitting, by the transceiver unit [304] at the SCSCF module [302] to the CTAS instance [402], a periodic health check query;
- receiving, by the transceiver unit [304] at the SCSCF module [302] from the CTAS instance [402], a response for the periodic health check query, wherein the response is one of a positive response and a negative response; and
- adding, by the CTAS manager [306] at the SCSCF module [302], the CTAS instance [402] in the active pool of one or more CTAS instances, in an event the positive response is received.
2. The method [500] as claimed in claim 1, wherein the adding, by the CTAS
manager [304] at the SCSCF module [302], the CTAS instance [402] in the
active pool of one or more CTAS instances facilitates acceptance of one or
more new calling requests at the CTAS instance [402].

3. The method [500] as claimed in claim 1, wherein the blacklisting the CTAS instance [402] is further based on an event where a number of service unavailable responses in the set of service unavailable response is more than a pre-defined threshold.
4. The method [500] as claimed in claim 1, wherein the set of service unavailable response is received at the transceiver unit [304] at the SCSCF module [302] after executing a graceful shutdown command received from a command line interface and shutting down gracefully one or more ongoing sessions associated with the CTAS instance [402].
5. The method [500] as claimed in claim 1, wherein the event is a planned event.
6. A system [300] for managing a graceful shutdown of a Converged Telephony Application Server (CTAS) application for an event, the system comprising:
- a Serving Call Session Control Function (SCSCF) module [302], the SCSCF module [302] further comprising:
o a transceiver unit [304] configured to receive, from a Converged Telephony Application Server (CTAS) instance implementing the CTAS application, a set of service unavailable response for one or more calling requests, and o a CTAS manager [306] connected to at least the transceiver unit [304], the CTAS manager [306] configured to:
▪ blacklist the CTAS instance [402] based at least on the
received set of service unavailable response, and ▪ remove the CTAS instance [402] from an active pool of one or more CTAS instances stored at a storage unit [308] at the SCSCF module [302]; wherein the transceiver unit [304] is further configured to:

transmit, to the CTAS instance [402], a periodic health check query,
receive, from the CTAS instance [402], a response for the periodic
health check query, wherein the response is one of a positive
response and a negative response, and
wherein the CTAS manager [306] is further configured to add the CTAS
instance [402] in the active pool of one or more CTAS instances, in an
event the positive response is received.
7. The system [300] as claimed in claim 6, wherein the CTAS manager [306] is configured to add the CTAS instance [402] in the active pool of one or more CTAS instances to facilitate acceptance of one or more new calling requests at the CTAS instance [402].
8. The system [300] as claimed in claim 6, wherein the CTAS manager [306] is configured to blacklist the CTAS instance [402] further based on an event where a number of service unavailable responses in the set of service unavailable response is more than a pre-defined threshold.
9. The system [300] as claimed in claim 6, wherein the set of service unavailable response is received after executing a graceful shutdown command received from a command line interface; and shutting down gracefully one or more ongoing sessions associated with the CTAS instance [402].
10. The system [300] as claimed in claim 6, wherein the event is a planned event.