I need to splice out the audio feed from the hand set line (4P4C jack) to a 3.5mm audio port on a computer to interoperate the call via speech recognition. I do not meddle around too much with analog signals, nor have I messed around with phone lines. I have found several pinout guides for the 4P4C connector, but not the technicalities I need to abide by. The primary guide I was referring to was:
My overall plan was to cut a pre-existing handset coord and splice out the green and red lines. The mic lines black and yellow are not needed and will be left alone. The red wire will be tied to a potentiometer for varying volume and to satisfy the schematic (a \$500 \mbox{ } k\Omega\$ one is laying around). The audio will then be supplied to a 3.5mm jack red on the center ring with the green on the ground ring (the ring furthest from the tip). This will then be feed into the light blue jack on a computer.
Any advice? I would not like to plug this into my sound card and trash my audio in, or the whole sound card.