Mute / Attenuator Lead - How to use?

[Nguy]

Hey, I just installed a deck for a friend of mine, it has an attenuator lead.

It's supposed to work in conjunction with a cellphone? How does one go about using this lead? Thanks a bunch!

Pioneer DEH-7500 MP in case anyone's wondering.

[blue LEDz]

i can honestly say i have never installed one. as far as i know you need to use it in conjunction with the phone stands/adapters that plug it into the car. my friend's aunt has her volvo with a small speaker and mic up in the top of the driver's side A-pillar, and when her phone rings, the radio mutes, and she pushes a button and looks like she's talking to herself

[Nguy]

That would be slick! All I know is that when the lead grounds, the att turns on. If there's a way we could hook this up to a cellphone adapter of some sorts, it would be intense!