GM Service Manual Online
For 1990-2009 cars only

The cellular phone system will turn itself on each time the ignition is turned on. You can press and hold the PWR button on the portable handset to turn it on and off. The phone will turn itself off after the ignition has been turned off and RAP has not been active for 20 seconds or more, unless a call is in progress.

You can make a call by entering the phone number and pressing the SEND button on the portable handset. You can use the portable handset to make calls this way even if it is docked. While the portable handset is docked, the call will be carried by the audio system speakers and the hands-free microphone. If you make a call this way it will not be recognized as the last number dialed by the steering wheel controls or the voice recognition. See Cellular Phone System Steering Wheel Controls and Voice Recognition for more information. To end a call made with the portable handset, press the END button on the portable handset or the END steering wheel control.