w4 ch13

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary goal of IMS in the telecommunications world?

To provide differentiation in services and strengthen customer relationships (correct)

To replace traditional telephony services

To offer cheap or free calls over the Internet

To adopt proprietary solutions

What type of sessions can IMS provide?

Only non-real-time multimedia sessions

Only video sessions

Both real-time and non-real-time multimedia sessions (correct)

Only voice sessions

What is the main advantage of IMS in the telecommunications world?

It is a standardized solution (correct)

It is only available for mobile networks

It provides low-quality services

It offers proprietary solutions

What is the primary focus of IMS?

Convergence of services supplied by different types of networks Signup and view all the answers

What is the role of IMS in the telecommunications world?

To provide standardized multimedia services Signup and view all the answers

What is the main benefit of IMS for operators?

Reducing subscriber churn Signup and view all the answers

What is the main goal of IMS for subscribers?

To offer personalized services Signup and view all the answers

What is the key way to retain subscribers according to IMS?

Building on and strengthening customer relationships Signup and view all the answers

What is the main goal of IMS in Next Generation Networks (NGNs)?

To make convergence between any IP networks and vertical handoff Signup and view all the answers

Which of the following is NOT a component of IMS architecture?

DNS Server Signup and view all the answers

What is the role of HSS in IMS architecture?

To provide user authentication and authorization Signup and view all the answers

Which IMS component is responsible for routing mobile-to-mobile calls?

I-CSCF Signup and view all the answers

What is the purpose of IMS-based interworking architecture?

To enable communication between two different IP networks Signup and view all the answers

What is the role of P-CSCF in IMS architecture?

To act as a proxy for user equipment Signup and view all the answers

Which IMS component is responsible for user registration and re-registration?

S-CSCF Signup and view all the answers

What is the primary function of S-CSCF in IMS architecture?

To manage session setup and control Signup and view all the answers

What is the primary function of the IMS?

To provide all network entities and procedures for real-time voice and multimedia IP applications Signup and view all the answers

What is the role of the Serving CSCF (S-CSCF)?

To interact with the Home Subscriber Server (HSS) for user authentication Signup and view all the answers

What is the main difference between 3GPP Release 5 and 3GPP Release 6?

Release 5 supports non-real-time services, while Release 6 supports real-time services Signup and view all the answers

What is the role of the Proxy CSCF (P-CSCF)?

To act as a proxy for user requests Signup and view all the answers

What is the primary function of the Interrogating CSCF (I-CSCF)?

To find the next hop for routing user requests Signup and view all the answers

What is the role of SIP in the IMS architecture?

To support signaling and session control for real-time services Signup and view all the answers

What is the main goal of IMS standardization?

To support any IP access network, including fixed and wireless networks Signup and view all the answers

What is the role of the Home Subscriber Server (HSS) in the IMS architecture?

To store user profile information Signup and view all the answers

What is IMS also known as?

Multimedia NGN (Next Generation Network) Signup and view all the answers

Who can deploy IMS?

Any entity, including those without an access or transport network Signup and view all the answers

What does IMS offer to make interoperability of new MM services easier?

Standardized service enablers and network interfaces Signup and view all the answers

What is the primary goal of IMS for operators?

To protect the operator business model and generate new revenue Signup and view all the answers

How does IMS solve service scalability?

By offering support to compose services and expand existing services Signup and view all the answers

What is the core of IMS?

Combining the best of datacom and telecom industries Signup and view all the answers

Why is IMS important?

Because it enables the creation and delivery of PS-based person-to-person MM services Signup and view all the answers

What type of decision is IMS deployment considered?

A strategic business decision Signup and view all the answers

What is the role of the S-CSCF in the IMS architecture?

Interfaces with internal and external service platforms Signup and view all the answers

What is the function of the I-CSCF in the IMS architecture?

Selects an S-CSCF in the home network for this user session Signup and view all the answers

What is the role of the P-CSCF in the IMS architecture?

Forwards the SIP request to the I-CSCF Signup and view all the answers

What is the function of the MRFC in the IMS architecture?

Interprets signaling information from an S-CSCF Signup and view all the answers

What is the function of the MRFP in the IMS architecture?

Provides resources to be controlled by the MRFC Signup and view all the answers

What is the role of the BGCF in the IMS architecture?

Forwards the session signaling to the appropriate MGCF and BGCF Signup and view all the answers

What type of platforms can the S-CSCF interface with?

SIP application servers, Open Service Access (OSA) Service Capability Servers, and IP Multimedia Service Switching Functions Signup and view all the answers

Where does the initial SIP request from a mobile travel to first?

The P-CSCF Signup and view all the answers

What type of services can a SIP server provide in addition to session control?

Value-added services Signup and view all the answers

What enables operators to leverage existing infrastructure for IMS services?

CAMEL Service Environment (CSE) Signup and view all the answers

What interfaces with the CSE by CAP?

IM-SSF Signup and view all the answers

What is the primary function of the OSA application server framework?

To enable third-party applications to secure access to the IMS Signup and view all the answers

What does the OSA application server interface with through the OSA API?

OSA SCS Signup and view all the answers

What type of services can be developed using the OSA application server framework?

Third-party applications that are not owner of the network infrastructure Signup and view all the answers

What do the OSA SCS and IM-SSF interface with respectively?

CSCF and CSE Signup and view all the answers

What is the primary function of the IM-SSF?

To host CAMEL features Signup and view all the answers

What is the primary consideration for IMS deployment?

Strategic decision Signup and view all the answers

What is the benefit of IMS for operators in terms of revenue?

Protects the operator business model and generates new revenue Signup and view all the answers

What is the core of IMS combining?

The best of two worlds: datacom industry and telecom industry Signup and view all the answers

What does IMS offer to make interoperability of new MM services easier?

Standardized service enablers and network interfaces Signup and view all the answers

What is the impact of IMS architecture on service scalability?

It solves service scalability Signup and view all the answers

Who can deploy IMS?

Any entity that decides to start an activity in IP services Signup and view all the answers

What is the primary goal of IMS for operators?

To protect the operator business model and generate new revenue Signup and view all the answers

What is IMS also known as?

Next Generation Network (NGN) Signup and view all the answers

What is the primary function of the P-CSCF in the IMS architecture?

To forward SIP REGISTER requests from a mobile to the mobile's home network Signup and view all the answers

What is the main function of the I-CSCF in the IMS architecture?

To select an S-CSCF for a user's session Signup and view all the answers

What is the purpose of the P-CSCF compressing and decompressing SIP messages?

To minimize the air-interface time Signup and view all the answers

What is the role of the P-CSCF in forwarding SIP messages from a mobile to a SIP server?

It determines to which SIP server the messages should be forwarded based on the result of the SIP registration process Signup and view all the answers

What is the role of the I-CSCF in hiding an operator's network internal structure?

It is used to hide an operator's network internal structure from an external network Signup and view all the answers

What is the role of the P-CSCF in detecting emergency sessions?

It is responsible for detecting emergency sessions Signup and view all the answers

What is the role of the P-CSCF in maintaining a security association with the mobile?

It maintains a security association with the mobile Signup and view all the answers

What is the role of the P-CSCF in creating CDRs?

It is responsible for creating CDRs Signup and view all the answers

What is the primary function of the S-CSCF in the IMS architecture?

To act as a SIP Registrar and accept users' SIP registration requests Signup and view all the answers

What is the main task of the S-CSCF in session control?

Relaying SIP requests and responses between calling and called parties Signup and view all the answers

What is the role of the P-CSCF in the IMS architecture?

To act as a SIP Proxy Server and relay SIP messages between users and other CSCFs Signup and view all the answers

What is the function of the Policy Control Function (PCF) in the P-CSCF?

To control the policy regarding how bearers in the packet-switched network should be used Signup and view all the answers

What is the relationship between the S-CSCF and the HSS?

The S-CSCF makes users' registration and location information available to the HSS Signup and view all the answers

What is the purpose of the S-CSCF in relation to application servers?

To interact with application servers and other IP or legacy service platforms Signup and view all the answers

What is the primary function of the S-CSCF in relation to user sessions?

To maintain session states for a registered user's on-going sessions Signup and view all the answers

What is the role of the P-CSCF in relation to mobile devices?

To act as a SIP Proxy Server and relay SIP messages between mobiles and other servers Signup and view all the answers

What is the main goal of IMS in Next Generation Networks (NGNs)?

To make convergence between any IP networks and a vertical handoff Signup and view all the answers

What is the primary function of IMS-based interworking architecture?

To enable communication between different IP networks Signup and view all the answers

What is the role of IMS in the telecommunications world?

To enable communication between different IP networks Signup and view all the answers

What is the primary focus of IMS?

To enable communication between different IP networks Signup and view all the answers

What is the main advantage of IMS for subscribers?

Seamless handovers between different IP networks Signup and view all the answers

What is the role of the S-CSCF in the IMS architecture?

To handle user registration and re-registration Signup and view all the answers

What is the role of the P-CSCF in the IMS architecture?

To act as an entry point for mobile users Signup and view all the answers

What is the primary function of the IMS-based interworking architecture?

To enable communication between different IP networks Signup and view all the answers

What is the main role of the IMS in Next Generation Networks (NGNs)?

To provide converged services between different IP networks Signup and view all the answers

What is the focus of the IMS-based interworking architecture for NGN networking?

To provide converged services between different IP networks Signup and view all the answers

What is the primary advantage of IMS for operators?

Increased revenue generation Signup and view all the answers

What is the role of IMS in achieving service convergence?

To enable service convergence between different IP networks Signup and view all the answers

What is the primary goal of IMS standardization?

To enable interoperability between different IP networks Signup and view all the answers

What is the benefit of IMS for subscribers?

Access to converged services across different IP networks Signup and view all the answers

What is the key to IMS-based revenue generation for operators?

Leveraging existing infrastructure for IMS services Signup and view all the answers

What is the primary consideration for IMS deployment?

Business model and revenue generation Signup and view all the answers

What is the main advantage of IMS in terms of service delivery?

Enhanced interoperability of new MM services Signup and view all the answers

What enables operators to create and deliver person-to-person MM services more effectively?

IMS deployment Signup and view all the answers

What is a key benefit of IMS architecture?

Enhanced scalability Signup and view all the answers

What is the core of IMS?

Combining the best of two worlds: datacom industry & telecom industry Signup and view all the answers

Who can deploy IMS?

Either traditional service providers or new entities Signup and view all the answers

What type of decision is IMS deployment considered?

Strategic business decision Signup and view all the answers

What is a key benefit of IMS for operators?

Generation of new revenue Signup and view all the answers

What does IMS offer to make interoperability of new MM services easier?

Standardized service enablers and network interfaces Signup and view all the answers

What is the main benefit of IMS for end-users?

New, exciting services and enhancements of existing services Signup and view all the answers

What is the role of the IMS in supporting IP multimedia sessions?

To provide real-time voice and multimedia IP applications Signup and view all the answers

What is the primary goal of IMS standardization?

To support both real-time and non-real-time services Signup and view all the answers

What is the main advantage of IMS for operators in terms of revenue?

Increased ARPU through new services Signup and view all the answers

What is the role of SIP in the IMS architecture?

To support signaling and session control for real-time services Signup and view all the answers

What is the main benefit of IMS for service convergence?

Single platform for multiple access networks Signup and view all the answers

What is the primary goal of IMS in terms of network architecture?

To provide a single platform for multiple access networks Signup and view all the answers

What is the main advantage of IMS in terms of interoperability and standardization?

Interoperability with multiple access networks Signup and view all the answers

What type of interface does the S-CSCF use to interface with all service platforms?

ISC interface Signup and view all the answers

What is the primary function of the OSA application server framework?

To provide open access to 3rd party service providers Signup and view all the answers

What protocol is used over the ISC interface for signaling?

SIP Signup and view all the answers

What type of services can be developed using the OSA application server framework?

Value-added services (VAS) and operator-specific services Signup and view all the answers

What is the role of the S-CSCF in the IMS architecture?

To control session establishment and release Signup and view all the answers

What does the OSA SCS interface with?

Application servers Signup and view all the answers

What is the primary benefit of IMS for operators in terms of revenue?

Increased revenue from value-added services Signup and view all the answers

What is the primary consideration for IMS deployment?

Interoperability with legacy networks Signup and view all the answers

What is the primary function of the Multimedia Resource Function Processor (MRFP)?

To provide resources to be controlled by the MRFC, including media streams processing and tones and announcements Signup and view all the answers

What is the role of the Breakout Gateway Control Function (BGCF)?

To select the PSTN network to which a session should be forwarded and forward the session signaling to the appropriate MGCF and BGCF Signup and view all the answers

What type of platforms can the S-CSCF interface with?

All of the above, including SIP-based application servers, Open Service Access (OSA) Service Capability Servers, and IP Multimedia Service Switching Functions (IM-SSF) Signup and view all the answers

What is the primary function of the Multimedia Resource Function Controller (MRFC)?

To interpret signaling information from an S-CSCF or a SIP-based Application Server and control the media streams resources in the MRFP Signup and view all the answers

Where does the initial SIP request from a mobile travel to first?

The visited P-CSCF Signup and view all the answers

What is the primary function of the I-CSCF in the IMS architecture?

To select an S-CSCF in the home network for the user session Signup and view all the answers

What is the primary function of the S-CSCF in the IMS architecture?

To interface with internal and external service platforms Signup and view all the answers

What is the primary function of the MRFP in relation to media streams?

To provide resources to be controlled by the MRFC, including media streams processing and tones and announcements Signup and view all the answers

What type of services can the S-CSCF interface with, according to the ISC interface?

Operator-specific services Signup and view all the answers

What protocol is used for signaling over the ISC interface?

SIP Signup and view all the answers

What is the primary function of the OSA application server framework?

Providing open access to 3rd party service providers Signup and view all the answers

What does the OSA SCS interface with?

Application Servers Signup and view all the answers

What is the primary consideration for IMS deployment?

Interoperability Signup and view all the answers

What enables operators to leverage existing infrastructure for IMS services?

IMS standardization Signup and view all the answers

What type of services can be developed using the OSA application server framework?

Value-added services Signup and view all the answers

What is the primary function of the IM-SSF?

Interface with Legacy Service Platform Signup and view all the answers

What is the primary advantage of IMS for end-users?

New, exciting services and enhancements of existing services Signup and view all the answers

What is the primary goal of IMS standardization?

To provide a standard for any IP access network Signup and view all the answers

Which of the following is a type of CSCF in IMS architecture?

Serving CSCF (S-CSCF) Signup and view all the answers

What is the primary role of IMS in terms of revenue generation?

To increase ARPU Signup and view all the answers

What is the primary function of SIP in IMS architecture?

To support session control and signaling Signup and view all the answers

What is the primary goal of IMS in terms of service convergence?

To provide the same services regardless of terminal and access type Signup and view all the answers

What is the primary benefit of IMS in terms of interoperability?

To make interoperability of new multimedia services easier Signup and view all the answers

Which release of 3GPP is targeted at supporting real-time services?

Release 6 Signup and view all the answers

What is the main driver for operators to rapidly push IMS?

Subscriber churn due to competition from new service providers Signup and view all the answers

What is the primary advantage of IMS in terms of service convergence?

Enabling convergence of services supplied indifferently by different types of networks Signup and view all the answers

What is unique about IMS in the telecommunications world?

It is the only standardized solution Signup and view all the answers

What is the primary function of the MRFP in the IMS architecture?

Provides resources to be controlled by the MRFC Signup and view all the answers

What is the role of the BGCF in the IMS architecture?

Forwards the session signaling to the appropriate MGCF and BGCF in the destination PSTN network Signup and view all the answers

What type of relationships can IMS help build?

Business-to-business relations Signup and view all the answers

What type of platforms can the S-CSCF interface with?

SIP-based Application Server, Open Service Access (OSA) Service Capability Server (SCS), and IP Multimedia Service Switching Function (IM-SSF) Signup and view all the answers

What is IMS designed to provide?

Real-time and non-real-time multimedia sessions Signup and view all the answers

Where does the initial SIP request from a mobile travel to first?

P-CSCF Signup and view all the answers

What is a key benefit of IMS for operators?

Differentiation in areas like personalization and service bundling Signup and view all the answers

What is the primary function of the MRFC in the IMS architecture?

Interprets signaling information from an S-CSCF or a SIP-based Application Server Signup and view all the answers

What is a key aspect of IMS architecture?

New concepts, new technologies, new partners and ecosystem Signup and view all the answers

What is a key goal of IMS?

To target convergence of services supplied indifferently by different types of networks Signup and view all the answers

What is the primary consideration for IMS deployment?

Interoperability and standardization Signup and view all the answers

What type of services can be developed using the OSA application server framework?

A wide range of services, including SIP-based and IP Multimedia Services Signup and view all the answers

What enables operators to leverage existing infrastructure for IMS services?

IMS standardization and interoperability Signup and view all the answers

What is the primary function of the OSA application server framework?

To enable third-party applications to access IMS Signup and view all the answers

What type of services can a SIP server provide in addition to session control?

Various value-added services Signup and view all the answers

What enables operators to leverage existing infrastructure for IMS services?

CAMEL Service Environment (CSE) Signup and view all the answers

What interfaces with the CSE by CAP?

IM-SSF Signup and view all the answers

What do the OSA SCS and IM-SSF interface with respectively?

OSA application server and CSE Signup and view all the answers

What is the primary function of the IM-SSF?

To host the CAMEL features and interface with the CSE Signup and view all the answers

What type of services can be developed using the OSA application server framework?

Third-party applications Signup and view all the answers

What does the OSA application server interface with through the OSA API?

OSA SCS Signup and view all the answers

What is the main reason why IMS is seen as a key solution for operators to retain subscribers?

To build on and strengthen the customer relationship Signup and view all the answers

What is the primary focus of IMS in terms of network convergence?

Convergence of services supplied indifferently by different types of networks Signup and view all the answers

What is the main advantage of IMS being a standardized solution?

It enables rapid deployment and adoption by different operators Signup and view all the answers

What type of multimedia sessions does IMS provide in addition to real-time sessions?

Non-real-time multimedia sessions Signup and view all the answers

What is the primary benefit of IMS standardization for end-users?

Faster time to market with new services Signup and view all the answers

What is the main challenge faced by operators in today's competitive market?

Subscriber churn due to cheap calls over the Internet Signup and view all the answers

Which type of access network is NOT explicitly mentioned as part of the IMS scope in 3GPP Release 7?

GPRS Signup and view all the answers

What is the main benefit of IMS for operators in terms of services?

It enables them to offer converged services Signup and view all the answers

What is the main role of IMS in the telecommunications world?

To provide a standardized solution for converged services Signup and view all the answers

What is the primary function of the Serving CSCF (S-CSCF)?

Session control and signaling Signup and view all the answers

What is the key difference between 3GPP Release 5 and 3GPP Release 6?

Support for real-time services Signup and view all the answers

What is the main focus of IMS in terms of subscriber relationships?

To retain existing subscribers Signup and view all the answers

What is the primary benefit of IMS for operators in terms of controlling CAPEX and OPEX?

Reduced CAPEX and OPEX Signup and view all the answers

What is the primary function of the Proxy CSCF (P-CSCF)?

Interworking with the access network Signup and view all the answers

What is the primary focus of IMS standardization in 3GPP Release 7?

Extension to any IP access network Signup and view all the answers

What enables IMS to provide a flexible and scalable architecture for operators?

Use of CSCFs for signaling and session control Signup and view all the answers

What is the primary function of the MRFP in the IMS architecture?

Provides resources to be controlled by the MRFC Signup and view all the answers

What is the role of the BGCF in the IMS architecture?

Forwards the session signaling to the appropriate MGCF and BGCF in the destination PSTN network Signup and view all the answers

What type of platforms can the S-CSCF interface with?

SIP application server, Open Service Access (OSA) Service Capability Server (SCS), and IP Multimedia Service Switching Function (IM-SSF) Signup and view all the answers

Where does the initial SIP request from a mobile travel to first?

Visited P-CSCF Signup and view all the answers

What is the primary function of the MRFC in the IMS architecture?

Controls the media streams resources in the MRFP Signup and view all the answers

What is the role of the I-CSCF in the IMS architecture?

Selects an S-CSCF in the home network for a user session Signup and view all the answers

What is the primary function of the S-CSCF in the IMS architecture?

Interfaces with internal and external service platforms Signup and view all the answers

What type of media streams does the MRFP process?

Audio, video, and other media streams, including transcoding and analysis Signup and view all the answers

What is the primary role of the OSA SCS and IM-SSF in the IMS architecture?

To act as gateways to other service environments Signup and view all the answers

What is the purpose of the CSE in IMS?

To enable legacy Intelligent Network services Signup and view all the answers

What is the primary function of the OSA application server framework?

To provide a standardized way for third-party applications to access IMS Signup and view all the answers

What interfaces with the CSE by CAP?

IM-SSF Signup and view all the answers

What type of services can be developed using the OSA application server framework?

Value-added services developed by third parties Signup and view all the answers

What is the primary advantage of using the CSE in IMS?

It enables operators to leverage existing infrastructure for IMS services Signup and view all the answers

What is the primary function of the IM-SSF?

To host CAMEL features and interface with the CSE Signup and view all the answers

What is the primary consideration for IMS deployment?

Leveraging existing infrastructure Signup and view all the answers

What is the primary purpose of IMS-based interworking architecture?

To enable convergence between IP networks and facilitate vertical handoff Signup and view all the answers

What is the main benefit of IMS in Next Generation Networks (NGNs)?

Facilitating convergence between IP networks and vertical handoff Signup and view all the answers

Which component is responsible for routing mobile-to-mobile calls in IMS architecture?

BGCF Signup and view all the answers

What is the primary role of the IMS in NGNs?

To facilitate convergence between IP networks and vertical handoff Signup and view all the answers

Which IMS component is responsible for user registration and re-registration?

HSS Signup and view all the answers

What is the primary goal of IMS in NGNs?

To facilitate convergence between IP networks and vertical handoff Signup and view all the answers

What is the primary purpose of IMS-based interworking architecture?

To facilitate convergence between IP networks and vertical handoff Signup and view all the answers

What is the primary role of IMS in NGNs?

To facilitate convergence between IP networks and vertical handoff Signup and view all the answers

Study Notes

Introduction to IMS

IMS (IP Multimedia Subsystem) is a standardized solution in the telecommunications world.
It is a new architecture based on new concepts, new technologies, new partners, and ecosystem.
IMS provides real-time and non-real-time multimedia sessions over an all-IP network.

IMS Architecture

IMS is divided into three different types of CSCFs (Call Session Control Functions):
- Serving CSCF (S-CSCF)
- Proxy CSCF (P-CSCF)
- Interrogating CSCF (I-CSCF)
IMS uses SIP (Session Initiation Protocol) to support signaling and session control for real-time services.

IMS Components

MRFP (Multimedia Resource Function Processor) provides resources to be controlled by the MRFC.
- Sources media streams (for multimedia announcements)
- Processes media streams (e.g., audio transcoding, media analysis)
- Tones and announcements (applied on receipt of ACK, self-timed with BYE, or stopped on BYE)
- Supports DTMF within the bearer path.
MRFC (Multimedia Resource Function Controller) interprets signaling information from an S-CSCF or a SIP-based Application Server and controls the media streams resources in the MRFP accordingly.
BGCF (Breakout Gateway Control Function) selects to which PSTN network a session should be forwarded.

IMS Benefits

Offers standardized service enablers and network interfaces for easier interoperability of new multimedia services.
Enables operators to create and deliver person-to-person multimedia services in a way that protects the operator business model and generates new revenue.
Provides service scalability by combining the best of two worlds: datacom industry and telecom industry.

IMS Standardization

IMS was initially standardized by 3GPP (3rd Generation Partnership Project) as part of its Release 5 specifications.
Release 6 supports real-time services.
Release 7 standardization extends IMS scope to any IP access network, including fixed access networks (e.g., DSL).

IMS Call Flow

Registration and re-registration process
Basic message flow
Routing of mobile-to-mobile calls - session initiation

IMS (IP Multimedia Subsystem)

Also known as Multimedia NGN (Next Generation Network)
A strategic decision for service providers, not just a network technology decision
Can be deployed by traditional service providers or new entities entering the IP services market

IMS Benefits

Offers standardized service enablers and network interfaces for easier interoperability of new MM services
Enables creation and delivery of person-to-person MM services while protecting the operator business model and generating new revenue
Solves service scalability issues with its architecture
Supports composing services and expanding existing ones

IMS Architecture

Combines the best of both datacom and telecom industries
Core components include S-CSCF, P-CSCF, and I-CSCF

S-CSCF (Serving Call State Control Function)

Provides session control services for a user
Maintains session states for registered users and performs tasks such as:
- Registration
- Session control
- Proxy server
- Interactions with application servers
- Other functions (e.g., service-related event notifications, generating Call Detail Records)

P-CSCF (Proxy Call State Control Function)

A mobile's first contact point inside a local IMS
Acts as a SIP Proxy Server
Performs functions such as:
- Forwarding SIP requests from a mobile to the mobile's home network
- Forwarding SIP messages from the network to a mobile
- Compression and decompression of SIP messages
- Maintaining a security association with the mobile

I-CSCF (Interrogating Call State Control Function)

An optional function that hides an operator's network internal structure from an external network
Serves as a central contact point for sessions destined to a subscriber of that network
Selects an S-CSCF for a user's session based on capabilities required by the user

Application Servers

SIP Application Server: provides session control and value-added services
Camel Service Environment (CSE): provides legacy Intelligent Network (IN) services
OSA Application Server: provides a standardized way for third-party applications to access the IMS

Flow of Information

Registration and re-registration processes involve S-CSCF, P-CSCF, and I-CSCF
Basic message flow includes SIP registration, session establishment, and call setup
Mobile-to-mobile calls are routed through the IMS architecture

IMS Overview

IMS (IP Multimedia Subsystem) is the technology that will prevail in Next Generation Networks (NGNs) for converging IP networks and facilitating vertical handoff.
IMS is also known as Multimedia NGN.

IMS Architecture

IMS provides standardized service enablers and network interfaces for achieving interoperability of new multimedia services.
The core of IMS combines the best of two worlds: datacom industry and telecom industry.

IMS Components

Multimedia Resource Function Processor (MRFP): provides resources, sources and processes media streams, and supports DTMF within the bearer path.
Multimedia Resource Function Controller (MRFC): interprets signaling information and controls media streams resources in MRFP.
Breakout Gateway Control Function (BGCF): selects the PSTN network for a session and forwards session signaling to MGCF and BGCF in the destination PSTN network.

Service Architecture

The service architecture involves a SIP request from a mobile, which travels from the originating mobile to the visited P-CSCF, then to the I-CSCF (if used) in the originating mobile's home network.
The I-CSCF selects an S-CSCF in the home network for the user session and forwards the SIP request.
The S-CSCF interfaces with internal and external service platforms using the ISC interface and the signaling protocol is SIP.

IMS Standardization

IMS was initially standardized by 3GPP as part of Release 5 specifications, targeted at supporting non-real-time services.
Release 6 supports real-time services, and Release 7 extends IMS scope to any IP access network, including fixed access networks.

IMS Benefits

IMS offers standardized service enablers and network interfaces for achieving interoperability of new multimedia services.
IMS enables service scalability, supports composing services and expanding existing services, and protects the operator business model while generating new revenue.

IMS Types of CSCFs

Serving CSCF (S-CSCF)
Proxy CSCF (P-CSCF)
Interrogating CSCF (I-CSCF)

IMS Overview

IMS (IP Multimedia Subsystem) is a new architecture that provides real-time and non-real-time multimedia sessions over an all-IP network.
It targets convergence of services supplied by different types of networks, including fixed, mobile, and Internet.
IMS is standardized by the 3rd Generation Partnership Projects (3GPP).

IMS Standardization

IMS was initially standardized by 3GPP as part of its Release 5 specifications, targeting non-real-time services.
Release 6 targets real-time services.
Release 7 extends IMS scope to any IP access network, including fixed access networks, wireless local area networks (WLANs), and wireless metropolitan area networks (WiMAX).

IMS Architecture

IMS provides all network entities and procedures to support real-time voice and multimedia IP applications.
It uses SIP (Session Initiation Protocol) to support signaling and session control for real-time services.
IMS architecture consists of three types of CSCFs (Call Session Control Functions):
- Serving CSCF (S-CSCF)
- Proxy CSCF (P-CSCF)
- Interrogating CSCF (I-CSCF)

Service Platforms

There are three types of standardized platforms:
- SIP Application Server
- Open Service Access (OSA) Service Capability Server (SCS)
- IP Multimedia Service Switching Function (IM-SSF)
S-CSCF interfaces with internal and external service platforms.
OSA SCS and IM-SSF are gateways to other service environments.

SIP Application Server

A SIP server can provide various value-added services.
A lightweight SIP-based server enables the CSCF to utilize SIP-based services and interact with ISP application servers without additional components.

Camel Service Environment (CSE)

CSE provides legacy Intelligent Network (IN) services.
It allows operators to leverage existing infrastructure for IMS services.
CSE interacts with the CSCF through IM-SSF.

OSA Application Server

OSA application server framework provides a standardized way for third-party applications to access the IMS.
The OSA application server interfaces with the CSCF through the OSA SCS by OSA API.

Multimedia Resource Function (MRF)

MRF consists of two components:
- Multimedia Resource Function Processor (MRFP)
- Multimedia Resource Function Controller (MRFC)
MRFP provides resources to be controlled by the MRFC.
MRFC interprets signaling information from an S-CSCF or a SIP-based Application Server and controls the media streams resources in the MRFP accordingly.

Breakout Gateway Control Function (BGCF)

BGCF selects the PSTN network to which a session should be forwarded.
It is responsible for forwarding the session signaling to the appropriate MGCF and BGCF in the destination PSTN network.

Learning Objectives

Learn about the Architecture of IMS
Understand different working elements of IMS Core
Learn about IMS interfaces
Learn about Application Servers to provide functionality
Learn about Basic Call Flow in IMS

Learning Objectives

Learn about the Architecture of IMS
Understand the working elements of IMS Core
Identify IMS interfaces
Understand Application Servers to provide functionality
Learn Basic Call Flow in IMS

Introduction

Successful services are available on the Internet, including email, web browsing, chat, audio/video downloading/streaming, and internet telephony
Operators face the problem of subscriber churn due to cheap/free calls over the internet provided by new service providers
To retain subscribers, operators need to offer differentiation in personalization, service bundling, co-branding, business-to-business relations, tariffs, single sign-on, and quality of service

What is IMS?

IMS (IP Multimedia Subsystem) is a standardized solution in the telecommunications world
IMS provides real-time multimedia sessions (voice, video, conference) and non-real-time multimedia sessions (Push to talk, Presence, instant messaging) over an all-IP network
IMS targets convergence of services supplied by different types of networks (fixed, mobile, internet)

IMS Benefits

Quality of Service enhancements
Service Integration
Keeps charging with user relation
Ease of use and Security
Controlling CAPEX and OPEX

IMS Standardization

Initially standardized by 3GPP as part of Release 5 specifications
Release 6 targeted at supporting real-time services
Release 7 standardization for any IP access network, including fixed access networks (e.g., DSL)

IMS Architecture

IMS provides network entities and procedures to support real-time voice and multimedia IP applications
Uses SIP to support signaling and session control for real-time services
CSCFs can be divided into three types: Serving CSCF (S-CSCF), Proxy CSCF (P-CSCF), and Interrogating CSCF (I-CSCF)
Multimedia Resource Function Processor (MRFP) provides resources to be controlled by the MRFC
Multimedia Resource Function Controller (MRFC) interprets signaling information from an S-CSCF or a SIP-based Application Server and controls the media streams resources in the MRFP accordingly
Breakout Gateway Control Function (BGCF) selects to which PSTN network a session should be forwarded

Service Architecture

The S-CSCF is responsible for interfacing with internal and external service platforms
Three types of standardized platforms: SIP application server, Open Service Access (OSA) Service Capability Server (SCS), and IP Multimedia Service Switching Function (IM-SSF)

SIP Application Server

Provides various value-added services in addition to session control
A lightweight SIP-based server enables the CSCF to utilize the SIP-based services and interact with the ISP application servers without additional components

Camel Service Environment (CSE)

Provides legacy Intelligent Network (IN) services
Allows operators to leverage existing infrastructure for IMS services
The CSCF interacts with CSE through IM-SSF

OSA Application Server

Provides a standardized way for a third-party to secure access to the IMS
Interfaces with the CSCF through the OSA SCS by OSA API (Application Programming Interface)

Examples of Flow of Information

Registration and Re-Registration
Basic Message Flow
Routing of Mobile-To-Mobile Calls - Session Initiation

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about IMS, a standardized solution for telecommunications, and its architecture comprising three types of CSCFs. Understand how IMS enables real-time and non-real-time multimedia sessions over an all-IP network.