Try, you will see. I thing pin 8 to GND for recognize HeadSet and
pin 7 to GND if you have external switch to hang up/down a call.
2 Audio RIGHT (called SB) to +| |- to RIGHT jack
11 Audio LEFT to +| |- to LEFT jack
12 Audio GND to GND jack
+| |- is capacitor (I used 10uF / 16V). It is not necessary, I thing you don't need it to connect.
After this, you will hear Caller voice in your (Left or Right) Speaker of CAR-audio system. (I don't remember now)
Post here results, please, because some people still have questin about this. Good Luck my friend! Live in peace
http://www.nobbi.com/steck_s25.htm