Kyocera Car kit with no cell mute

I have a Kyocera car kit that does not have cell mute capabilites. My HU (JVC KD-DV6160) does support muting.  I was wondering if there was a way to get the cell mute work.  Maybe using relays or something to ground the mute wire on the Headunit.  A friend mentioned putting a relay that works off the wire to the speaker but I think the speaker's voltage may be way to low to trip the relay. My dad agreed and also said it could introduce noise.

I also thought about the Pioneer cd-cm1 cell Mute. It is a stand alone cell mute that can actually detect the cell signal when using the phone.  I just don't know if it is compatable with other head units besides pioneer models. There's not alot of info floating around about it.  I would really appreciate any help, I'm installing this as a christmas present for my wife.