Voice Feedback
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The OPC system has the capability of responding to the user with either an automated voice response or with a tone or beep. These 2 types of responses can be switched back and forth by pressing the answer/end call button, waiting for the system to respond with the words OnStar Ready and by stating the phrase, Voice Feedback. The system will then respond with, Voice Feedback Is Now On/Off.