Tag Archives: Application server

IMSSF and RIMSSF

This post particularly describes the gateways in IMS which communication back and forth with a legacy endpoints.To get a overview of IMS itself click here  and to get a detailed description of IMS and its architecture click here .

What is IM-SSF  ?

IP Multimedia Service Switching Function is a  gateway to provide IN service such s legacy VPN ( Virtual Private Network ).

IMSSFaltanai

IMSSF

 

What is R-IM-SSF  ?

Reverse IP Multimedia Service Switching Function Works on reverse principle to connect IN network  to IMS services using IMS services such as FMFM ( find me follow me ) .

RIMSSFaltanai


More link on telecom transformation , migration and inter-opereability :

Transformation towards IMS 

 

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JAIN SLEE

•Jain SLEE :- JAIN is a Sun Java standards initiative and part of the Java Community Process.
JAIN specifies a comprehensive range of APIs that target converged IP and PSTN networks, including APIs for

– High-level application development (such as service provider APIs and the Service Logic Execution Environment (SLEE))

– call control

– signalling at the protocol level (such as SIP, MGCP and SS7)

•For telephony, data and wireless communications networks, the Java APIs defined through.

– service portability

– network independence

– open development

•A Service Logic Execution Environment (SLEE) is high-throughput, low-latency, event-processing application environment.
•JAIN SLEE  is designed specifically to allow implementations of a standard to meet the stringent requirements of communications applications (such as network-signaling applications).

Goals of JAIN SLEE are:

– Portable services and network independence.

– Hosting on an extensible platform.

– services and SLEE platform available from many vendors.

Key Features are  :

•Industry standard :- JSLEE is the industry-agreed standard for an application server that meets the specific needs of telecommunications networks.
•Network independence:-The JSLEE programming model enables network independence for the application developer. The model is independent of any particular network protocol, API or network topology.
•Converged services:- JSLEE provides the means to create genuinely converged services, which can run across multiple network technologies.
•Network migrations :-As JSLEE provides a generic, horizontal platform across many protocols, independent of the network technology, it provides the ideal enabler technology for smooth transition between networks.
•Global market—global services:-JSLEE-compliant applications, hosted on a JSLEE application server are network agnostic. A single platform can be used across disparate networks
•Robust and reliable:- As with the enterprise application server space, deploying applications on a standard application server that has been tested and deployed in many other networks reduces logic errors, and produces more reliable applications
•Standard object orientated component  architecture

Scope of JAINSLEE applications

•The principal features of the JSLEE programming model are :

– programs written in Java

-asynchronous programming paradigm

-well-defined event-delivery semantics

-component-based, object-oriented approach

-transactional model

-“profiles” of information, which represent provisioned data

-usage interfaces that support gathering service statistics

-support for standard Java APIs (such as JNDI and JDBC), and optionally, support integration with J2EE

-standard facilities for traces, alarms and timers, for use by the applications that are hosted on the SLEE

Resource adaptors

-The JSLEE provides integration capabilities using a plug-in architecture known as the resource adapter

architecture. Resource adaptors (RAs) provide interconnection with the “outside” world, for example,

interfaces to communication protocol stacks, directory services or external systems.

•SLEE management

-The JSLEE specification also defines the management capabilities of the SLEE. It adopts the Java standard

in this area, Java for Management Extensions (JMX).

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IP Multimedia Subsystem ( IMS )

 IMS is a an architectural framework for IP based multimedia rich communications. It was standardized by a group called 3GPP formed in 1999.
It started as an enabler for 3rd generation mobile networks in European market and later spread to wirelne networks too . IMS became the key to  Fixed Mobile Convergence (FMC).
Based on IETF Protocols (such as SIP, RTP, RTSP, COPS, DIAMETER, etc.) , IMS is  now crucial for controlling conmmunication in a IP based Next Genration Network ( NGN ).
Communication service providers and telecom operators are migrating from circuit-switched networks to IMS technology with the increasing bandwidth (5G) and user expectations.
ims layers

Why IMS ?

Early days TDM networks were not robust enough to support emerging technologies and data networking. There was a need to migrate from voic eonly network to Triple play network ( voice , video and data ).

Other factors included :

  • rapid service development
  • service availiability in both home and roaming network
  • wireline and wireless convergence

Due to these above mentioned reasons TDM was outdated and IMS gained support .

 

What benefits does IMS bring ?

It offers counteless applications around rich multimedia services on wireless , packet swtched and even tradional circuit switched networks.

Easier to Create and Deploy New Applications and Services
  •  Enhanced applications are easier to develop due to open APIs and common network services.
  • Third-party developers can offer their own applications and use common network services, sharing profits with minimal risk
  •  New services involving concurrent sessions of multimedia (voice, video, and data) during the same call are now possible
  • Reduced time-to-market for new services is possible because service providers are not tied to the timescales and functions of their primary NEPs
Capture New Subscribers, Retain Current Subscribers
  • Better voice quality for business applications, such as conferencing, is possible
  • Wireless applications (like SMS, and so on) can be offered to wire line or broadband subscribers.
  • Service providers can more easily offer bundled services.
Lower Operating and Capital Costs
  • Cost-effective implementation of services is possible across multiple transports, such as Push-To-Talk (PTT), presence and Location-Based Services (LBS), Fixed-Mobile Convergence (FMC), mobile video services, and so on.
  • Common provisioning, management, and billing systems are supported for all networks.
  • Significantly lower transport costs result when moving from time-switched to packet-switched channels.
  • Service providers can take advantage of competitive offerings from multiple NEPs for most network elements.
  • IMS results in reduced expenses for delivering licensed content to subscribers of different types of devices, encodings, or networks.

 

The reason for widespread adoption of IMS is also that it follows standards and open interfaces  from 3GPP and ETSI, also is flexible for policy control , OSS/BSS , Value Added Services etc .

 

IMS features

1. Abstraction from Underlying Network :
IMS is essentially leading towards an open and standardized network and interface ,  irrespective of underlay network.
2. Fixed /Mobile Convergence 
Inter operability with Circuit Switched (CS) Mobile application Part (MAP)
3. Roaming 
Location awareness between home and visiting network.
4. Application layer Call Control
IMS application layer has the provision for defining proxy or B2BUA based call flow completion . This leads to operator being able to introduce business logic into call sessions.
IMS is supplemented by SIP (IETF ) , Diameter ( IETF) and H248(ITU-T). The release cycle of IMS is as follows :
  • 2002-03-14 Rel-5  : IMS was introduced with SIP. Qos voice over MGW.
  • 2004-12-16 Rel-6 : Services like emergency , voice call continuity , IPCAN ( IP connectivity Access Network )
  • 2005-09-28 Rel-7 : Single Radio Voice Call Continuity , multimedia telephony,eCall ,ICS
  • 2008-12-11 Rel-8 : IMS centralized services , supplementary services and internetworking between  IMS and  Circuit Switched Networks,charging , QoS
  • 2009-12-10 Rel-9 : IMS emergency numbers on GPRS , EPS(Enhanced packet system) , Custom alert tone , MM broadcast/Multicast
  • 2011-3-23 Rel-10 : home NodeB, M2M, Roaming and Inter UE transfer
  • 2012-09-12 Rel-11 :-tbd
  • 2014-09-17 Rel-12 :- tbd
  • 2015-12-11 Rel-13 :- tbd

IMS Layers

Majorly IMS is divided into 3 horizontal layers given below :

2014-05-24_0015

•Transport / MediaEndpoint Layer

Unifies transports and media from analog, digital, or broadband formats to Real-time Transport Protocol (RTP) and SIP protocols. This is accomplished by media gateways and signaling gateways.

It also includes media servers with media processing elements to allow for announcements, in-band signaling, and conferencing. These media servers are shared across all applications (voicemail, interactive response systems, push-to-talk, and so on), maximizing statistical use of the equipment and creating a common base of media services without “hard-coding” these services into the applications.

•Session and Control Layer

This layer arranges logical connections between various other network elements. It provides registration of end-points, routing of SIP messages, and overall coordination of media and signaling resources.

IMS core which is part of this layer primarily contains 2 important elements Call Session Control Function (CSCF) and Home Subscriber Server (HSS) database. These are explained below 

HSS Home Subscriber Server

It is a database of user profiles and location information . It is responsible for name/address resolution and also authorization/authentication .

CSCF Call Session Control Function

Handles most routing, session and security related operation for SIP messages . It is further divided into 3 parts :

  • Proxy CSCF: P_CSCF is the first point of contact from any SIP UA. It proxies UE requests to subsystem.
  • Serving CSCF: S-CSCF is a powerful part of IMS Core as it decides how UE request will be forwarded to the application servers.
  • Interrogating CSCF: I-CSCF initiates the assignment of a user to an S-CSCF (by querying the HSS) during registration.

•Application Services Layer

 The Application Services Layer contains multiple Application Servers (AS), such as:
  • Telephony Application Server (TAS) – for defining custom call flow logic
  • IP Multimedia Services Switching Function (IM-SSF)
  • Open Service Access Gateway (OSA-GW), and so on.

Additional Links :


Update on IMS :

IMS has been mandated as the control architecture for Voice over LTE (VoLTE) networks. Also IMS is being widely adopted to mange traffic for Voice over WiFi (VoWiFi) systems.