ITU-T J.178 PDF

This Recommendation describes the IPCablecom Call Management Server (CMS) to CMS signalling protocol intended for use by a CMS to communicate with another CMS in order to support packet-based voice and other real-time multimedia applications. The protocol exchanges between a CMS and a Media Gateway Controller (MGC) are identical to those between CMSs, and so for purposes of this Recommendation the MGC is considered identical to a CMS. CMSs currently support multimedia endpoints (within the IPCablecom infrastructure) that use the Network-based Call Signalling (ITU-T Rec. J.162) (NCS) protocol and the PSTN Gateway Call Signalling Protocol (ITU-T Rec. J.171.x) (TGCP) for communicating signalling information between the endpoint and the CMS. In the future, other protocols may be supported as well, and the CMS to CMS protocol is intended to be sufficiently general to accommodate such protocols without change.

The CMS to CMS protocol uses the Session Initiation Protocol 2.0 (SIP) specification with extensions and usage rules that support commonly available local and CLASS^SM services. This protocol is referred to as the Call Management Server Signalling (CMSS) protocol.

The CMSS protocol takes into account the need to manage access to network resources and account for resource usage. The usage rules defined in this Recommendation specifically address the coordination between CMS signalling and IPCablecom Dynamic Quality of Service (QoS) mechanisms for managing resources over the cable access network. In addition, this Recommendation defines the protocols and messages needed between Call Management Servers for supporting these services.

This Recommendation specifies the protocols and procedures to use between CMSs belonging to a single service provider as well as between CMSs that belong to different service providers. In the case that the CMSs are owned by multiple service providers, it is assumed that the service providers have a mutual trust relationship.

Other IPCablecom Recommendations describe interfaces between other system elements. These Recommendations cover areas such as: Event Message recording for billing and other back office functions (ITU-T Rec. J.164); Dynamic Quality of Service (ITU-T Rec. J.163); Operations and Provisioning (ITU-T Rec. J.167); and Security (ITU-T Rec. J.170). These other specifications indirectly place requirements on the signalling protocol to ensure that it transports the correct data needed to implement a complete system. This Recommendation includes syntax and protocols for implementing these requirements. Currently, this Recommendation does not address interworking with non-IPCablecom-compliant devices.

NOTE – Where this Recommendation discusses interworking with the PSTN, this is done purely to illustrate the behaviour of the CMS and MGC in the context of off-net originated or terminated calls. The primary purpose of this Recommendation is to describe CMSS signalling. A full specification of interworking with the PSTN is not provided by this Recommendation. Other Recommendations (such as ITU-T Rec. Q.1912.5 or IETF RFC 3398) describe detailed interworking between SIP and ISUP.