A method of managing registration of a User Equipment (UE) with an IP Multimedia Subsystem (IMS) via a Long-Term Evolution (LTE) network. The method comprises, following termination of a Voice over LTE (VoLTE) call, initiating a timer at the UE and, if no VoLTE call is initiated to or from the UE prior to expiry of the timer, then sending an IMS de-registration request from the UE to the IMS.