My contact couldn't see or hear me

Anytime you encounter audio or video issues, it's important to make sure that you are near strong wifi, and not outside or on weak cellular data. 

If the problem still exists on strong wifi, then you and your contact should both try leaving and rejoining the call to see if the issue fixes itself. Leaving the call will not end the call and you can always rejoin without any issues. 

Finally, please make sure that your microphone works. If you are using headphones with a microphone on them, please make sure that it is not damaged and that you have enabled all necessary permissions for the app.