Would the pic_list community help me with suggestions on 
 a circuit that can differentiate between an Telephone 
Service provider announcement: e.g "The number you are 
calling is unavailable" and a human answering the Telephone 
call on the other end. The circuit could be equipped to 
identify other Telephone Call Progress tones e.g busy tone, 
dial tone, ring tone. 

I would like to use this circuit in a pic-controlled 
telephone dialer.

Many thanks

Josh

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