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1/ Executive Overview
This document provides an overview of the Service Capability Interaction Management (SCIM) platform delivering service interaction and mediation solutions for telecom networks across multiple domains covering SS7 based networks, SIP/IMS networks and interaction with Web-Services. A SCIM provides fixed, mobile, cable, MVNO and alternative telecommunications service providers with a gradual migration path to IMS, leveraging existing legacy infrastructure and installed base, while making new investments in the IMS domain.
This document provides an overview of the Service Capability Interaction Management (SCIM) solutions for IMS and Pre-IMS networks. It describes the SCIM architecture while providing insight into the SCIM, service mediation and legacy integration capabilities as well as the overall platform architecture and design. Several solution configurations are presented to demonstrate typical IMS and pre-IMS configurations of the platform.
2/ Overview
The SCIM is a Service Capability Interaction Management (SCIM) platform enabling the control and orchestration of service delivery from multiple applications platforms for each session or call. The SCIM delivers full compliancy with IMS standard methodologies of service interaction and orchestration, including support for standard filter criteria processing, IMS policy management, and on-line/off-line IMS charging functions.
SCIM goes beyond the IMS domain and basic capabilities through an extensive set of advanced service interaction and discrimination features, for both the IMS domain as well as legacy and IT/SOA domains. These capabilities include comprehensive support for legacy telecom network technologies on both the application and switching/session control layers, enabling the delivery and interaction of services across both legacy and IMS telecom domains.
3/ Service Capability Interaction Management
The SCIM provides service capability interaction management for services from different domains (legacy, NGN, IMS) and from different platforms. The SCIM takes horizontal approach, when managing and orchestrating services from several domains and goes beyond standard IMS SCIM, when interacting with legacy services we well.
3.1/ SCIM overview
Service orchestration within the IMS domain is based on a concept of application chaining, in which, for the delivery of multiple applications for a single session, the session is routed sequentially between multiple application servers, acting typically as back-to-back user agents (B2BUA) or as SIP proxies. Thus, a “chain” of services is created, through which the session is passed allowing each application platform to perform its role in its turn. The SCIM Orchestration Engine processes filter criteria logic which defines which application servers should be invoked and the interaction adaptors within the SCIM that will be used to enable that.
3.2/ Service Orchestration in Legacy, NGN, and IMS Networks
Through the use of the legacy module adaptors, the SCIM expands the service orchestration capabilities beyond IMS. This enables the delivery of combined services from multiple domains including IMS-based service platforms and IN-based services platforms. Such combined service can seamlessly be delivered towards both legacy terminals (e.g. GSM, CDMA or fixed phones), and IMS clients, while acting as an integral part of the IMS architecture
The legacy application layer adaptor acts as a SIP AS towards the SCIM layer, allowing the SCIM layer to invoke legacy SCP transparently as part of the orchestration chain as if it was one of its application servers. Thus, the Orchestration Engine invocation of application chains is expanded, with the SCIM referring to the legacy application layer adaptors as regular IMS application servers, allowing the IN or IMS services to be combined seamlessly. Similarly, the legacy session layer adaptor interacts with the SCIM as an S-CSCF, allowing the SCIM to perform its orchestration and interaction management roles seamlessly and deliver the services to legacy devices.
As part of the support for pre-IMS networks, for networks lacking an HSS, the SCIM allows the control of service interaction based on standard parameters provisioned within the HLR, accessed via MAP/IS-41. Such parameters as the Service Key are mapped within the SCIM to preconfigured Shared iFC sets which are used to control the session.
4/ SCIM Use Cases
The SIP/IN SCIM is deployed as a network node in the IMS and SS7 networks, interacting with service and session/call control elements in the legacy SS7 network, as well as in the NGN SIP based network and the IMS core. The following section examines some common uses cases for the SIP/IN SCIM. The solutions shown below utilize different combinations and configurations of the SIP/IN SCIM, to achieve the various service interaction, orchestration and mediation network capabilities.
4.1/ IN Mediation
The SCIM IN Mediation solution enables the interworking of SCPs and SSPs/MSCs which use different implementations or variants of IN protocols.
As an example a combined CDMA/GSM operator, migrating the network to GSM, can use the SCIM to deliver services from its CAP based prepaid to its CDMA subscribers, consolidating the service layer of both networks. In this solution the SCIM interacts with the GSM SCP via CAMEL protocol, and interacts with the WIN based MSC. Another example is using the SCIM IN Mediation solution to adapt between different variants of protocols, for example, mediating between an SCP using a specific INAP variant and CAMEL, for operators who are looking to introduce new network equipment vendors into a previously single-vendor environment.
4.2/ IN Service Interaction
The SCIM IN Service Interaction solution allows the introduction of two or more SCPs in an IN network, such that operators can overcome the inherent limitation of IN implementations allowing only a single SCP to provide services per a single call. In this solution, the SCIM allows service combinations containing services running on a number of SCPs delivered for a single call.
A common use case is deployment of a Pre-paid SCP alongside a VPN SCP to deliver combined services. This is achieved by using the SCIM module that extends the interaction and execution of several services towards two or more internal IN adaptors.
The SCIM IN Interaction solution can also be combined with the IN mediation capabilities, such that multiple services with different IN protocols can be combine to a single service combination.
4.3/ Delivering Legacy Services for SIP Networks
The SCIM Legacy Services for SIP networks solution allows SIP softswitches to interact with legacy services running on existing IN SCP platforms. With this solution, operators who roll out new SIP networks can use the SCIM to leverage their existing deployed services towards their SIP based network and next generation clients.
A sample use case is of a mobile operator with a SIP network that uses the SCIM to deliver the existing IN based Prepaid service to its SIP based subscribers. Another example is of a wireline carrier that uses the SCIM to leverage their existing legacy service platforms such as Number Portability, Toll-Free etc. towards its SIP based subscribers. In this solution, the SCIM interacts via SIP with the Softswitch and acts as IM-SSF via the appropriate IN protocol with the IN service platform (SCP).
4.4/ Delivering SIP Services over IN/Legacy Networks
The SCIM SIP Services over IN solution allows the delivery of SIP services in legacy (non-SIP) networks. Using this solution, operators can start to deploy SIP/IMS based platforms for delivering services to the legacy domain, whether these services are delivered to mobile subscribers using 2G/2.5G/3G phones, or fixed POTS subscribers. By deploying SIP services today for non-SIP networks, operators are making a future proof investment that could be leveraged when new SIP/IMS networks are put into service.
As an example, a mobile GSM operator who considers expanding or replacing its current Voice VPN service platform, can avoid investment in a legacy, short term, IN solution. As an alternative the operator can deploy a SIP implementation of the Voice VPN service and use the SCIM to deliver the service over CAP to the GSM mobiles. This solution uses the legacy session layer adaptor towards the MSCs which act as a full standard SCP towards the switch while interacting via SIP with the application server.
4.5/ Converged Network with VCC
The Converged Network VCC solution provides service interaction capabilities towards both the SIP and the legacy domains and allows the introduction of dual mode handsets, with support for VCC (Voice Call Continuity) handover between WiFi and the 2G/3G mobile domain. This is achieved using the VCC module which interacts with the SCIM to deliver the VCC service towards any dual mode handset in the network. The VCC capability can be combined with any other service platform SIP or IN based to create a dual mode handset service combination.
4.6/ Converged Network SCIM
The SCIM Converged solution allows the introduction of multiple services for a single call, mobile or wireline, SIP or legacy. In this solution, the SCIM acts as a service interaction control layer, allowing the delivery of services from different technologies and different domains towards unified service combinations, such that users can enjoy blended services delivered from multiple platforms whether IN or SIP based.
4.7/ IM-SSF for IMS
The SCIM IM-SSF Solution for IMS networks allows IMS CSCFs to interact with legacy services running on existing SCP IN platforms. With this solution, operators who roll out new IMS networks can use the SCIM to leverage their existing, deployed, IN-based services towards their IMS core network.
As an example, a mobile operator introducing a CSCF and IMS clients into the network can use the SCIM to deliver its existing IN-based Prepaid service to its new IMS subscribers. Another example is of a wireline carrier that is introducing a TISPAN core network, and can leverage its existing legacy service platforms such as Number Portability and Toll-Free for the new TISPAN/IMS subscribers. In this solution the SCIM interacts via ISC with the CSCF and delivers a full IM-SSF implementation to interact via the required IN protocol with the IN service platform (SCP).
4.8/ IPTV integration
The SCIM orchestration capabilities include the interaction with services such as IPTV. The SCIM enables to control and interact between SIP services (such as Centrex), IN services (such as Prepaid) and IPTV service. Solution for IMS networks allows IMS CSCFs to interact with legacy services running on existing SCP IN platforms. With this solution, operators who roll out new IMS networks can use the SCIM to leverage their existing, deployed, IN-based services towards their IMS core network.
An example of such use case is an IPTV service that is influenced by an incoming voice call to the user’s mobile phone. The user define through browser its preferences: pause the video when call arrives, reject the call, continue the call with no change in the video status, pause the video when answering the call or invoke a fine/follow me service and forward the call to another number.
5/ IMS SCIM
The SCIM provides a high performance and robust service capabilities interaction management solution for the IMS core network. With comprehensive implementation of ISC, Cx/Sh, Ro/Rf protocols, SCIM manages the per session interaction between CSCF/Soft Switches, HSS, Online and Offline Charging Functions and the various application servers or IM-SSF/OSA gateways in the network. Service interaction is managed according to filter criteria stored in the HSS that allows assigning each IMS subscriber with his/her own unique service profile and service combination. Built for core network performance, the IMS SCIM delivers carrier grade reliability, availability, and scalability for IMS deployments.
Integrated with the SOA Services Framework, SCIM opens the door to dynamic interaction with Web Services and external SOA service bus, delivering a comprehensive service layer evolution path to IMS and beyond.
6/ Conclusion
The architecture presented in this document places the SCIM functionality in a key role for the network convergence and service providers’ migration to IMS. Through its extensive and seamless legacy network support, based on service independent normalization to SIP, it provides the service continuity capabilities, required for hybrid networks that evolve from Legacy, Pre-IMS to IMS and other IP services. It allows services to be delivered from Legacy platforms to the new SIP/IMS clients and SIP/IMS application platforms to the legacy domain. This allows for the seamless migration from Legacy to IMS, while allowing the full service continuity with those services already available in the network, and creating a new offering to operators that can now evolve their network to SIP, mostly throughout the application layer.
Author: Tal Zoller, Convergin and Francois Deza, BEA Systems
About Convergin
Convergin is the leading provider of Service Capability Interaction Management (SCIM) core network solutions. By utilizing Convergin's Accolade WCS, service providers accelerate their evolution towards IMS while enabling seamless orchestration of mobile, legacy, next generation and web services elements. For more information, please see www.convergin.com
7/ References Document
[1]. 3GPP TR 23.810 V0.8.0 (2007-10), 3rd Generation Partnership Project;
Technical Specification Group Services and System Aspects;
Study on Architecture Impacts of Service Brokering; Release 8
[2]. 3GPP TS 23.218 IP Multimedia (IM) session handling; IM call model; Stage 2.
[3]. 3GPP TS 22.228,Service requirements for the Internet Protocol (IP) multimedia core network subsystem (IMS); Stage 1
[4]. 3GPP TS 23.228, IP Multimedia Subsystem (IMS); Stage 2
[5]. 3GPP TS 24.229, Internet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3
[6]. 3GPP TS 23.278, Customized Applications for Mobile network Enhanced Logic (CAMEL) Phase 4; Stage 2; IM CN Interworking
[7]. 3GPP TS 29.278, customized Applications for Mobile network Enhanced Logic (CAMEL); CAMEL Application Part (CAP) specification for IP Multimedia Subsystems (IMS)
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