See also:

Parental Control
The RSE system may have a Parental Control feature, depending on the radio. To enable Parental Control, press and hold the radio power button for more than two seconds to stop all system features such ...

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 ...

Reactivation for Subsequent Owners
Push and follow the prompts to speak to an Advisor as soon as possible after acquiring the vehicle. The Advisor will update vehicle records and will explain the OnStar service offers and options ava ...