A method of transmitting information related to a multicast service in a Mobile Telecommunications network is provided. In one embodiment, the information related to the presence of cells in a registration area which are part of a multicast service area for the multicast service is transmitted between radio network controllers. In another embodiment, the information related to the multicast service one or more user terminals have joined is stored in a radio network controller while the user terminal has joined said one or more multicast services.