EE One is the term for when someone has both Mobile and Broadband linked on the same EE ID. This gives exclusive SIM Only and Flex Pay airtime offers, as well as adding an Unlimited Data Boost to any pay monthly lines on your account over £10pm.
See here for details: https://ee.co.uk/ee-one
If you have both services but are unable to link them in the EE App, I would advise calling customer services.
If you are currently only subscribed to one of these services, you can purchase the other through your EE App and this will link them automatically and you will then become an EE One customer.
