There is described a Session Initiation Protocol (SIP) network entity for operating in a communications channel between a first SIP end point and a second SIP end point in a communication network. The first SIP end point has available a first set of communication features and the second SIP end point has available a second set of communication features, including at least one communication feature, for example Music on Hold, that is unavailable to the first SIP end point. The network entity acts as a client application for the first SIP end point and as a server application for the second SIP end point and is arranged to exchange signaling information with the SIP end points to enable the second SIP end point to utilize the at least one communication feature during communications with the first SIP end point.