19. The invention as defined in claim 12 , wherein said apparatus classifies a plurality of input signal segments as being either speech or voice-band data in accordance with a sequential decision logic sequence which designates input signal segments as speech during a speech state and designates input signal segments as voice-band data during a voice-band data state.
19. The invention as defined in claim 12 , wherein said apparatus classifies a plurality of input signal segments as being either speech or voice-band data in accordance with a sequential decision logic sequence which designates input signal segments as speech during a speech state and designates input signal segments as voice-band data during a voice-band data state. 20. The invention as defined in claim 19 , wherein said apparatus, in accordance with said sequential decision logic sequence, switches from said speech state to said voice-band data state when results of said determining means for a plurality of input signal segments indicate that said speech state is erroneous, and said apparatus, in accordance with said sequential decision logic sequence, switches from said voice-band data state to said speech state when results of said determining means for a plurality of input signal segments indicate that said voice-band state is erroneous.