Why is my device being reported as lost or stolen to apple?

I have three iPhones 13 and 13pro

I use my devices with business att and recently they have been blocked from the network and are being reported as lost or stolen. How, why? They’re all my devices and I’ve been using them since I purchased them. I don’t k ow what the problem would be and I was informed I needed to call apple to let them know my devices aren’t lost.