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:
Keyless Trunk/Liftgate Opening
Press the trunk/liftgate release
button located above the license
plate to open the trunk/liftgate if the
keyless access transmitter is within
range. See Trunk (Sedan, Coupe) for additional
...
Place a Call Using a Stored
Number
1. Push . System responds:
“OnStar ready.”.
2. Say “Call <name tag>.”.
System responds: “OK,
calling <name tag>.” ...
Security
OnStar provides services like Stolen Vehicle Assistance, Remote Ignition
Block, and Roadside Assistance, if the vehicle is equipped with these services.
OnStar can unlock the vehicle doors remotely, ...