Using the “Dial” or “Call” Command
1. Press and hold 
for two seconds.
2. Say “Dial” or “Call.” 3. Say the entire number without pausing, or say the name tag.
Once connected, the person called will be heard through the audio speakers.
See also:
Roadside Assistance Program (U.S. and Canada)
For U.S.-purchased vehicles, call 1-888-881-3302; (Text Telephone (TTY): 1-888-889-2438).
For Canadian-purchased vehicles, call 1-800-268-6800.
Service is available 24 hours a day, 365 days a year.
...
Taillamps, Turn Signal, Sidemarker, Stoplamps, and Back-Up Lamps
A. Stop/Tail/Turn Signal/ Sidemarker Lamp
B. Auxiliary Taillamp
C. Back-up Lamp ...
Interior
Depending on the Silverado Hybrid's seating configuration, the crew cab can
seat five or six people. Interior features include:
Hybrid badge on tachometer
Fuel economy gauge
Optional navigation ...