Hey Danjp1,
We’d be happy to help out. We understand you’re having issues with Facetime calls where you’re unable to hear or see the other party and vice versa.
To clarify, are you running iOS 16.4.1? If not, we’d suggest getting fully updated and testing further using the steps here: Update your iPhone or iPad - Apple Support
If the issue persists, it’d also be a good idea to turn off both iMessage and FaceTime, restart, and enable these features again for use and test further. For help with doing so, work through the steps here:
Check your device settings
1. Make sure that you’re connected to a cellular data or Wi-Fi network.
2. If you're using an iPhone, you need SMS messaging to activate your phone number with iMessage and FaceTime. Depending on your carrier, you might be charged for this SMS.
3. Go to Settings > General > Date & Time and make sure that your time zone is set correctly.

Turn off and restart iMessage and FaceTime
1. Go to Settings > Messages and turn off iMessage.
2. Go to Settings > FaceTime and turn off FaceTime.
3. Restart your device:
* iPhone
* iPad
* iPod touch
4. Turn iMessage and FaceTime back on.
This is outlined further here: If you can’t turn on or sign in to iMessage or FaceTime - Apple Support
If all else fails, we’d suggest working with Apple for further support on the matter from here. They can be reached using this link: Get Support
Take care!