A user entity (UE) such as a smartphone is configured to connect to both WiFi and a Long Term Evolution (LTE) cellular network for voice and data services. For voice, the UE supports both Voice over LTE (VoLTE) and Voice over WiFi (VoWiFi). When the UE is connected to VoWiFi and roaming from a first WiFi access point to a second WiFi access point, the UE and Mobility Management Entity in the cellular network carry out a preparatory handover to VoLTE to prevent service loss in the event of an unsuccessful VoWiFi connection from the second WiFi access point.