The phone, if installed, is in the armrest. The phone buttons on the steering wheel and radio mute and unmute the radio, and allow you to control the phone. If you don't have the phone, all the buttons do is mute/unmute the radio. The phone, a motorola startac, is impossible to get service for in the US, unless you happen to have the euro GSM version. The phone interface is a box, two wiring harnesses, a custom armrest phone holder, and the phone itself.