A system and method of registering a voice over LTE (VoLTE) capable vehicle telematics unit with a wireless carrier system includes: detecting at the vehicle telematics unit a wireless signal broadcast by a cell tower; determining from the wireless signal whether the cell tower provides cellular service using a VoLTE cellular protocol; and when it is determined that the cell tower does not provide cellular service using the VoLTE protocol, then preventing the VoLTE-capable vehicle telematics unit from attempting to wirelessly connect with the cell tower using an IP multimedia subsystem (IMS) protocol.