Hey, jimrecht,
Thanks for posting in the Apple Support Communities about your AirPods. If I understand, they are connecting and playing audio just fine, right up until you place a call and the other person answers. When they do, the call audio switches from the AirPods to the phone. I'm happy to help!
Based on what you've described, I'd recommend first force closing any open app you have: How to force an app to close on your iPhone, iPad, or iPod touch - Apple Support, then restarting the iPhone: Restart your iPhone, iPad, or iPod touch - Apple Support.
Next, make sure your iOS software is up to date: Update your iPhone, iPad, or iPod touch - Apple Support.
If the audio still switches from the AirPods to the phone, try resetting the AirPods and connecting them again: Reset your AirPods - Apple Support.
Enjoy your weekend!