Proactive registration probes are conducted by an eCall-only IVS prior to an emergency to determine network availability and which available roaming networks a registration request will be approved by the home network. The results of this probing are stored and managed by the IVS. If no suitable roaming network can be found (or if only limited service is available, and this limited service cannot support an eCall), the IVS may notify the driver that the emergency call service may not be available. The frequency of the probing may be increased or decreased based on a variety of factors, including whether the IVS is currently receiving home network service, roaming network service, or no service, as well as whether the vehicle is moving and whether probing has previously been completed for a particular area (using location information, for example).