It's more that most phones support most of the bands all the US providers use, so when the roaming policy changes, a lot of the phones will still work. The phon

It's more that most phones support most of the bands all the US providers use, so when the roaming policy changes, a lot of the phones will still work. The phone will be able to register with the roaming network. Also, they can set up the antennas to broadcast on multiple MNCs, so it looks like a native network (i.e. T-Mobile can run LTE towers that broadcast as both the T-Mobile and old Sprint network so all Sprint phones can connect without a problem) (of course, this depends on Boost phones supporting VoLTE).