Circuit Lake

Electronic Project and Circuit Collection

Home Phone Caller Filter and Blocker

07/16/2012 Category: Interfacing, Miscellaneous, PIC

BALSAMO is dsPIC-based incoming calls filter for your line phone. It can be used to ‘block’ a hidden or blacklisted number. Doragasu, project designer, implemented Caller ID protocol in the firmware due to lack of Caller ID decoder IC.

PIC-based Home Phone Caller Blocker

The project has signal conditioning stage, a hardware RING detector, a dsPIC30F6014 to control everything and process the input signal, 2×16 LCD for display, LEDs and some pushbuttons. It also equipped with relay to pick up/hang the phone, a serial port RS232 for debugging and a microSD card reader.

How it works
The system is in Sleep mode until a RING is detected by the hardware RING detector. Then the dsPIC wakes up, and starts the ADC and demodulator stages. Once the calling number is decoded, it’s displayed in the LCD. If it’s a hidden number, or it’s blacklisted, the relay is activated to pick up the phone, and then it is deactivated to hang the phone.