This article explains what to do if FaceTime Audio (the version of the app that only supports audio) isn't working on your device, or if you're having issues with FaceTime sound.
How to Fix FaceTime Audio Problem
There are several reasons why FaceTime Audio is not working. The most common reason is that you do not have a compatible device or operating system.
This is especially true for iPhones older than the iPhone 4 (for example, the iPhone 3) and the first-generation iPad.
Other possible reasons why you have no audio in FaceTime include:
