Patent ID: 7983310

Claim:
An in-band signaling modem for use in a digital wireless telecommunications device to send input data over a voice channel of a digital wireless telecommunications network, the in-band signaling modem comprising: software stored in a memory in the wireless telecommunications device, the software executable in a processor in the wireless telecommunications device; the software configured to control the processor to generate a predetermined first signaling waveform for transmission over the voice channel, the first signaling waveform having a frequency within a range of approximately 400-3400 Hz; wherein the first signaling waveform is tapered at the beginning of the first signaling waveform, such that it gradually increases in amplitude from substantially zero amplitude to a predetermined peak amplitude, for reducing distortion of the first signaling waveform by a transmission-side vocoder in the voice channel; the software further configured to input the first signaling waveform to the transmission-side vocoder to prepare the transmission-side vocoder for processing audio frequency tones that encode the input data prior to sending the input data over the voice channel; wherein the first signaling waveform is tapered at the end of the first signaling waveform, such that it gradually decreases in amplitude from the peak amplitude to substantially zero amplitude; and the first signaling waveform has a duration within a range of approximately 1-3 seconds; and wherein the software is further configured to control the processor to generate a combination signaling waveform for transmission over said voice channel, the combination signaling waveform comprising the first signaling waveform and a second signaling waveform, the second signaling waveform characterized by FSK (frequency shift keying) modulation of two audio frequencies; and the first and the second signaling waveforms are transmitted in tandem.