Recommendation ITU-T Q.3622 v.1 specifies requirements for supplementary service such as a communication waiting (CW) to be provided on the IMS platform. The version number, v.1, indicates that this is version one of Recommendation ITU-T Q.3622, and that it relates to Release 10 of the relevant 3GPP/ETSI standard. This Recommendation endorses ETSI TS 124 615 V10.6.0 (2015-07) "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Communication Waiting (CW) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol Specification (3GPP TS 24.615 version 10.6.0 Release 10)".