Patent ID: 8180406

Claim:
A method of establishing a voice call involving a mobile device, comprising: starting a local ring tone at the mobile device after sending voice call setup information from the mobile device on a data channel; receiving on a voice channel, at the mobile device, an incoming call; sending one or more primarily verification DTMF tones on the voice channel; concurrently with the sending of the one or more primarily verification DTMF tones on the voice channel, restarting the local ring tone; if the one or more primary verification tones are not acknowledged on the voice channel within a pre-determined delay, sending one or more secondary verification DTMF tones, different from the primary verification tones, on the voice channel; and if the one or more secondary verification DTMF tones are not acknowledged within the pre-determined delay, repeating the sending of the one or more primary verification DTMF tones.