Hi there User007007,
From what we can tell, you're hearing static audio from your iPhone during FaceTime calls. We're glad you've joined us in Apple Support Communities, and we can provide some guidance.
To start, you'll want to check your sound settings and try cleaning the receivers and speakers on your iPhone. Follow the steps in this link to do so, and be sure to have a look at the other suggestions mentioned:
If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
If that doesn't seem to help, and you're not hearing static with any other types of audio like music or recorded videos, the issue is most likely network-related. Have a look at the 'If you have connection or sound quality issues with FaceTime' section at the bottom of this support article to learn more:
If you can't make a FaceTime call on your iPhone, iPad, or iPod touch
We hope this provides some clarity about the behavior you're experiencing with FaceTime on your iPhone.
Cheers.