Patent ID: 6381472
Filing Date: 2002-04-30
Classification: H04W

Abstract:
A mobile switching center, comprising:a digital switch for establishing selective connections of a port to circuits going to digital wireless base stations; demultiplexer means, coupled to the port of the digital switch, for separating digital messages representing predetermined tone signals compatible with a data device for an impaired user from vocoded speech samples in a data stream received from one of the wireless base stations; a vocoder coupled to the demultiplexer means for digitally decoding the vocoded speech samples into representations of analog audio signals; a decoder, coupled the demultiplexer means, for decoding the digital messages to identify the predetermined tones; a generator responsive to the decoder, for producing representations of the predetermined tones; and a combiner, coupled to the vocoder and the generator, for combining the representations of analog audio signals and the representations of the predetermined tones into a signal stream for transmission over a telephone network.