Phones can only use the bands they pass through FCC compliance on. There are examples of some phones that had bands software disabled that they passed through c

Phones can only use the bands they pass through FCC compliance on. There are examples of some phones that had bands software disabled that they passed through compliance on. (AT&T was notorious for disabling band 4 in their handsets in software during 3G era, as this was T-Mobile's main 3G band) The story here is that AT&T incorrectly messaged and issued press releases that many older models had bands disabled in software and would just receive an update to supoort C-band, but that wasn't the case.