scope:

The present document 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 the present document the MGC is considered identical to a CMS. CMSs currently support multimedia endpoints (within the IPCablecom infrastructure) that use the Network-based Call Signaling [24] (NCS) protocol and the PSTN Gateway Call Signaling Protocol [25] (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 CLASSSM services. This protocol is referred to as the Call Management Server Signaling (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 the present document specifically address the coordination between CMS Signaling and IPCablecom Dynamic Quality of Service (QoS) mechanisms for managing resources over the cable access network. In addition, the present document defines the protocols and messages needed between Call Management Servers for supporting these services.

The present document 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 documents describe interfaces between other system elements. These documents cover areas such as: Event Message recording for billing and other back office functions [23]; Dynamic Quality of Service [21]; Operations and Provisioning [i.8]; Electronic Surveillance [22]; and Security [26]. These other specifications indirectly place requirements on the signalling protocol to ensure that it transports the correct data needed to implement a complete system. The present document includes syntax and protocols for implementing these requirements. Currently, the document does not address interworking with non-IPCablecom-compliant devices.