As long as the sim as been activated on Fi, it can be used in any compatible phone, but on T-Mob only, which isn't that big of a deal since Sprint stinks so bad anyway. The only other feature that doesn't work is the WiFi calling, but most ppl I know that have turned this feature off anyway since it causes calls to drop when switching between WiFi and Cell service. Voicemail and such works since it uses Google Voice and the app can be installed for that.