Alpine 9835 mute wire

Hi guys, Does anyone know if there is a special mute wire on alpine 9835? Here is what I am trying to do. I just installed motorol hf850 bluetooth hands free kit in my Audi (it came out to be sweet install I will post pics soon). Only problem is that I have to trun the volume on my car stereo my self to make a call and if my stereo is playing loud enought I cant hear a call coming. The HF850 has a mute wire, that if connected correctly it will automatically mute the car stereo when making/receiving a call. On my apline 9835 there is no specific mute wire. so I was wondering if anyone know of a work around so that I can connect the mute wire from my hands free kit to the alpine 9835. Thanks for your help guys.

I don't remember exactly, but I had that unit a few months back & pretty sure it had a muting wire - pink, maybe? - marked "int"(?).  Never used it, but I believe that's what it was for.

alpines radios have a pink wire that is used for muting.......hook your handsfree mute wire to it and ur good to go.....

While we're at it, what sort of input is that wire looking for - positive, negative or either?  And when it sees it, what's the result - does it shut off all sound or just tone it down?  Is it abrupt or gradual?