What's my number?
This page is for devices with calls and mobile data.
Open Phone > Menu (upper left) > Phone Preferences.
If your phone number is stored on your SIM card, it appears under Phone Number at the top of the Phone Preferences screen. Not all wireless service providers put phone number information on the SIM card.
Checked against the LuneOS code and installed apps. Nobody has tried these steps by hand yet, so tell us if something differs.