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:
When to Check
Check the tires once a month or more.
Do not forget the spare tire. See Full-Size Spare Tire for additional
information. ...
Customer Assistance Offices (Mexico)
To contact the Customer Assistance Center (CAC), use the phone numbers listed
in this section. Customer assistance is available Monday through Friday, 08:00 to
20:00 hours, and Saturdays from 08:0 ...
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. ...