See also:

Cellular and GPS Antennas
Avoid placing items over or near the antenna to prevent blocking cellular and GPS signal reception. Cellular reception is required for OnStar to send remote signals to the vehicle. ...

Liftgate
WARNING Exhaust gases can enter the vehicle if it is driven with the liftgate or trunk/hatch open, or with any objects that pass through the seal between the body and the trunk/hatch or liftgate. ...

Muting a Call
To Mute a Call Turn or press the MENU/SELECT knob and select Mute Call. To Cancel Mute Turn or press the MENU/SELECT knob and select Mute Call. ...