In a nutshell...if you are used to the Verizon features such as Visual Voicemail, Call Filter, Digital Secure (or whatever it's called now because I think they may have changed that one)...those won't be available on an unlocked phone. You can download the My Verizon app and that ought to work, but you would have to use either the native features built into the S21 or download 3rd party apps for the other stuff.Samsung has been moving away from using their own apps built into phones in the last year or 2, so very recent factory unlocked Samsung phones (I think it started with the S23 and newer) rely a bunch on the Google apps installed.