Without phone signal, the app functions the same as when you have no data connection: you can view the location of any what3words address you enter. You can also navigate to it using compass mode.
To share a what3words address over the phone or in a text message you need phone signal. To load maps, or share in other apps or social media, you need a data connection.
Watch our CEO Chris explain how what3words works offline here.
*Please be aware phone cases with magnetic closures might impact accuracy when using the compass mode.