on 20-10-2017 13:39
Here is an extract fromtheir email
Unfortunately due to tablets being unable to receive a text verification code it is not possible to registereschedule your number for O2 priority. The text message is required for authentication and verification purposes.
Not a really helpful response IMHO
on 20-10-2017 13:57
Only ipads can't receive the code directly, but still ways around that.
Any android tablet can even if you have to download an app off play store.
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone7 (EE)