A first computing device receives over a telecommunications network from a second computing device a verification message encrypted using a public key. The verification message is generated by the second computing device when initiating a call to the first computing device. The first computing device transmits to a wireless router via a wireless local area network (WLAN) created by the wireless router, the encrypted verification message. The first computing device receives from the wireless router over the WLAN, a decrypted verification message decrypted from the encrypted message by the wireless device using a private key associated with the public key. The first computing device transmits over the telecommunications network to the second computing device, the decrypted verification message. If the second computing device determines that the decrypted verification message corresponds to the encrypted verification message, the second computing device allows the call to the first computing device to proceed.