I am currently grandfathered on ATT unlimited plan. However without subsidized phones, the 100 dollar cell phone bill plus the monthly cost of a phone is a bit much. I am contemplating switching to Boost mobile for the unlimited plan. However, If I get the ATT iPhone 7 I can't use the phone on boost, is mu=y understanding. But If I purchase the verizon phone, I could continue to use it on ATT but could switch to boost If I so chose. Do I have this correct? It seems like the better option would be to buy the verizon iPhone 7 , and continue to use it on ATT but be able to switch if I wanted,