Circuit Lake

This project is a dialer box that connects to the phone and can be used to store and dial phone numbers, pins, and credit card numbers. The project uses PIC 16F690 microcontroller and a NTE1690 DTMF dialer chip.

Because this is an IP phone and I cannot just send the DTMF tones over the line, the easiest place to plug in the box is between the phone and the handset. The box has two RJ9 ports at the back – one gets connected to the headset’s port on the phone, the other to the headset itself. The dial tones are sent over the microphone line. This way, it works both on IP-phones, and on standard (old fashioned, non-IP) ones.

DTMF Phone
Schematic and Source code
avtanski.net