Unable to Connect to OnStar Message
If there is limited cellular coverage or the cellular network has reached maximum capacity, this message may come on. Push 
to try the call again or try again after driving a few miles into another cellular area.
See also:
Playing an MP3 or WMA (in Either the DVD or CD Slot)
If a disc is inserted into the top DVD slot, the rear seat operator can turn on the video screen and use the remote control to navigate the CD (tracks only).
(Tune): Turn to select MP3/WMA files.
...
Making a Call
To make a call:
1. Press 5 once or twice (depending on the radio).
2. Enter the phone number.
3. Select Call to start dialing the number. ...
Electronic Range Select (ERS) Mode
ERS or manual mode allows for the selection of the range of gear positions. Use
this mode when driving downhill or towing a trailer to limit the top gear and vehicle
speed. The shift position indi ...