The disclosed technology automatically terminates wireless service that a mobile communication network provided to a telematics unit, e.g. when the customer is no longer active for telematics service. The disclosed deactivation allows the network service provider to reuse any resources, such as mobile numbers, that were previously assigned to the particular telematics unit. In a disclosed example, a SMS deactivation message causes the telematics unit to delete its mobile provisioning data, such as its MDN and/or its MIN, and replace that data with a dummy number. The deactivation procedure may also provide a replacement destination number for emergency calls, typically a cleared number, such as 911. For example, the deactivated telematics unit would be able to call a PSAP, and the PSAP would recognize that the unit is inactive for wireless service (and cannot be called-back) from the dummy number used to identify the unit.