A wireless device and a receiving computing system communicate over a carrier network. The wireless device submits a request for service to the receiving computing system, which then returns an authentication key. The authentication key is routed using the telephone number stated in the request for service as being associated with the wireless device. However, the authentication key is dispatched over a different data transport mechanism. For example, the request may be submitted using an IP data transport mechanism, while the authentication key is returned using an SMS data transport mechanism. The wireless device then evidences, through appropriate communication, that the wireless device both submitted the request and received the response. Accordingly, the telephone number is verified as being associated with the telephone number.