BASCOM-AVR : [help] Detection of an incoming call : NEWTOPIC

My use the ATMega8535 and telephone siemens c55, I try make program to receive calls incoming in order that turn on buzzer, I yet to find's how ??? [b:167c908aa8][color=red:167c908aa8](BASCOM-AVR version : 2.0.7.3 , Latest : 2.0.7.6 )[/b:167c908aa8][/color:167c908aa8]