not receiving Facetime calls

My macbook air can make facetime calls but not receive calls. Why?

I don't have any other apple products. This is the brand new m1 Macbook air.

When someone with an iphone receives my facetime call they see my email as the number that callled. But when they push that call history to call my back, it shows up as a missed call instantly in my facetime call history, it doesn't ring or give me an option to pick up the call.