I've taken my samsung galaxy s4 to europe with no problem using a local sim card there. Planning on getting one for Kolbi when in Costa Rica in March. We have a local (VERY local) carrier here in rural Oklahoma and their tech department is non-existent. I know the band's for the s4 will match up with those used in CR for regular use and 3G, but have no idea about the "lock/unlocking" of the phone I've seen posts about. Since I've used in overseas before, I'm guessing its unlocked?? How the heck would I know otherwise?