Provided the IMEI number will show it is compatible with the new plan. You can buy an unlocked phone but there is no guarantee that it is compatible. If the phone is bought through Visible it will be. If it is iPhone it seems like when I have checked a few of the current models it doesn't ask for an IMEI number, or whatever iPhone uses, like an Android. Here is the checker https://www.visible.com/shop/compatibility
