hi Andy and Babar

first Andy No receiver will not send any DTMF to indicate that he has received the call. i have to detect that the call has been received.


Thanks Babar for giving these comments. yes now i have a picture clear to me about how to detect all those tones and how to process.


okey let me clear here, if there is no tone at all on the phone line then there will be just DC on IRQ/CP pin. and if there is any tone like noraml telephone tone when telephone goes off hook, busy signal, dialing signal and othere there frequencies will be being directed to the CP pin and i have to program the uC to detect these tones.


now if 8880 is directly connected to the telephone line, does 8880 provides features like ON HOOK or OFF HOOK and how can i go OFF HOOK from OFF HOOK.

what will happen when a telephone call is being received, i mean the TELCO send i think 90V AC dialing siganl to the receiver. how will 8880 behave to this when this siganl arrives. so again how will i go ON HOOK to OFF HOOK to receive that call.


you talk about measuring frequencies lengths and some comparision operation through which i can detect various tones, suppose i design some thing with this concept and the device is working in pakistan, will it also work outside pakistan. i mean do i have to face different standards.



Shahzad