Hi babar,

thanks for the reply, this week end was good to me in this, as i connected to telephones in series with 12V powe supply and with a resister in betwwen and they worked as mentioned in the article in downloaded from net. when when i press any key on first phone i can hear the tone on the other phone means the other phone is getting the DTMF. also yes i have purchased two MT8880 chips and i at this point i have gone through its data sheet. so now what i will try on the next ween end is that connect one phone with this chip and try to make this chip to send and receive DTMF tones from the phone connected in series. i think i know the theory so i can do easily hopefully. okey as you mention in the forum that you will give me some directional help for this 8880 chip here are some of them conceren.


- which pin on the 8880 will connect to Tone, Tip (red, green) lines of the telephone. i know there are DTMF in and DTMF out pins on the chip.

- can this chip handle audio, i mean can this chip send audio.

- i could not determine how can i detect with this chip that my call has been accepted on the other party.

- okey i need some education, what is the difference between Tone and Pulse, i think tone is the combination of two frequencies which represent the key pressed. what is the standard in pakistan, pulse, tone


any way thakns for the assistance.

Thanks
Shahzad