I don't want any one to think that iam trying to get something from this forum without doing any kind of hard work.... my only question is:- Just like we can use assembly coding for microcontroller to detect Pulse Dialing from a telephone set. Can we use controller to detect Tone Dialing that is DTMF dialing.. considering the factors of low band & high band and their electrical sum of frequency. do we have to do some PWM or any other technqiue... i know that we can write codes to generate Tone Dialing from the controller but is it possible to use controller to detect Tone Dialing... without using MT8870 or any DTMF decorder.