Patent ID: 7747281

Claim:
A portable device comprising: a digital processor arranged to implement an in-band signaling modem for receiving digital data over a digital voice channel of a wireless communications network, the digital processor adapted to execute software, and the software stored in a computer-readable storage medium disposed in the portable device; and wherein the software is arranged to implement an input that receives voice signals over the digital voice channel of the wireless communications network; a filter that detects synthesized tones representing the digital data that is interleaved with the voice signals transmitted over the digital voice channel, the synthesized tones synthesizing frequency characteristics of human speech and preventing voice encoding circuitry in the wireless telecommunications network from corrupting the digital data represented by the synthesized audio tones; and a demodulator that converts the detected synthesized tones back into the represented digital data; wherein the filter includes: a first in-band filter for detecting signals outside of a predetermined synthesized tone frequency band; a second out-of-band filter for detecting signals inside the synthesized tone frequency band; and a comparator that compares the signals detected outside the synthesized tone frequency band with the signals detected inside the synthesized tone frequency band and identifies signals as synthesized tones when the compared value is greater than a selected value.