Old iPhone rings when someone calls my new iPhone

I upgraded to a new iPhone 13and now my iPhone 6 and my iPhone XR rings any time they are connected to Wi-Fi, even with no Sim card. I changed carriers when I got my 13 but kept my old number. I have tried to de-register iMessage and FaceTime on the old phone but it says I have to do it on the new phone too. So I did. And then I re-registered the new one but the old one picked back up. What should I do to get the old one disassociated with my number?