Three-Way Calling
Three-way calling must be supported on the cell phone and enabled by the wireless service carrier.
1. While on a call, press 
.
2. Say “Three-way call.” 3. Use the dial or call command to dial the number of the third party to be called.
4. Once the call is connected, press to link all callers together.
See also:
Maintenance Replacement Parts
Replacement parts identified below by name, part number, or specification can
be obtained from your dealer.
...
Roof Rack System
WARNING
If something is carried on top of the vehicle that is longer or wider than the
roof rack—like paneling, plywood, or a mattress—the wind can catch it while the
vehicle is being driven. ...
Retrieve My Number
1. Push X. System responds: “OnStar ready.”
2. Say “My Number.” System responds: “Your OnStar Hands-Free Calling number is.” ...