I have two Iphone 7. One I tranfer from Verizon to here sucessfully.
Now I want to transfer the other identical Iphone 7 but was told it is not compatible, why?
Your second iPhone 7 model may be different and may not have CDMA which is required for XM.
You may want to preorder an iPhone SE 2020 from XM, or any other iPhone, as they are offering $200 off while supplies last, and then transfer your other non compatible iPhone 7 line.