Emergency
With Automatic Crash Response, the built-in system can automatically connect to help in a crash even if you cannot ask for it.
Push 
to connect to an Emergency Advisor. GPS technology is used to identify the vehicle location and can provide critical information to emergency personnel. The Advisor is also trained to offer critical assistance in emergency situations.
See also:
Storing a Radio Station as a Favorite
To store a station as a favorite:
1. Tune to a radio station.
2. Press the FAV button to display the page where the station will be stored.
3. Press and hold one of the six softkeys until a beep so ...
Onstar.com
The website provides access to account information, manages the OnStar subscription,
and allows viewing of videos of each service. Get subscription plan pricing and
sign up for OnStar Vehicle Diag ...
Customer Assistance for Text Telephone (TTY) Users (U.S. and Canada)
To assist customers who are deaf, hard of hearing, or speech impaired and who use Text Telephones (TTYs), GMC has TTY equipment available at its Customer Assistance Center. Any TTY user can communicat ...