I am making a DTMF decoder but I need to answer the phone itself. I have an old nokia phone(c1-01) witch doesn't have autoanswer mode. It has a 3.5 mm(4poles) jack as input.I don't want to take it apart, I want access to answer mode only by 3.5mm jack. I have searched for some diagrams on google but didn't work. So does anyone knows any circuit diagram that can solve my problem?