how can i make a connection between gsm phone and DTMF decoder?
(link : https://www.instructables.com/id/Cellphone_operated_Robot/)
i have a motorla l6 phone with me and i'm planning to use that in the circuit. It has auto-answer option. But it has an USB port to connect the headset. If i want to use it, is it ok if cut one of the ear phones and connect the wire at the 2nd pin of DTMF IC?
The next thing is what is the significance of word "RING" written at the ground in the circuit (left side at the bottom)