The DTMF dialer / tone generator I made using the TCM5089 chip works fine and will send the DTMF tones over a land line, or even when plugged into the headset jack of a wireless land line phone, but when the same output is plugged into the headset jack of a cell phone no tones are heard over the open connection. If the tone generator is output to a small speaker, and acoustical coupling is used by placing the wired headset mic next to the speaker, then the tones can be heard over the open cell connection. I would like to eliminate this inefficient accoustical coupling, and bypass the speaker to mic combination.
I think it has to do with the cell phones using true digital signals, and not analog, but how can a tone be sent to the cell phone and be heard as if you are physically pressing one of the cell phone buttons? This is not necessarily to do the initial dialing, but after the call is established to be able to send tones over the open phone line?
Any suggestions would be sincerely welcomed.
Michael
I think it has to do with the cell phones using true digital signals, and not analog, but how can a tone be sent to the cell phone and be heard as if you are physically pressing one of the cell phone buttons? This is not necessarily to do the initial dialing, but after the call is established to be able to send tones over the open phone line?
Any suggestions would be sincerely welcomed.
Michael