This Recommendation defines the stage-2 service description for the IP Multimedia Core Network Subsystem (IMS), which includes the elements necessary to support IP Multimedia (IM) services. [ITU-T I.130] describes a three-stage method for the characterization of telecommunication services, and [ITU-T Q.65] defines stage-2 of the method. The Third Generation Partnership Project (3GPP) has developed the specification in a form optimized for the wireless environment. This Recommendation references the ETSI version of the 3GPP specification and specifies only the modifications necessary to optimize it for the cable environment. It is an important objective of this work that interoperability between IPCablecom 2.0 and 3GPP IMS is provided. IPCablecom 2.0 is based upon 3GPP IMS, but includes additional functionality necessary to meet the requirements of cable operators. Recognizing developing converged solutions for wireless, wireline, and cable, it is expected that further development of IPCablecom 2.0 will continue to monitor and contribute to IMS developments in 3GPP, with the aim of alignment of 3GPP IMS and IPCablecom 2.0. Because ITU-T Recommendation indicates modifications from the ETSI specification [ETSI TS 123 228], the structure of the Recommendation does not follow normal ITU-T practice, to ease the task of the reader to correlate the two documents. The modifications are shown in clause 6.