HoW do I make an ATT interface from car radio?

I bought a Sony CDX-CA810X car cd player and it has an ATT wire for coneccting to a moblie phone interface so that when the phone rings the radio mutes. But the damn installation instructions don't tell you how to conect this wire. Could any one help me please?

If its a genuine nokia carkit that you ae installing its the little yellow wire that connects to the radio mute.

if in not a genuine nokia kit then it could be any wire

Hope this helps

Best Regards

Mark

thanx marky