Message “Your EE account is not eligible to enable mobile data. Contact EE at 150 for more information”

This question has been resolved by me:

Using iPhone 11 A2221 iOS 16.2 / Apple Watch Ultra model A2684 / Apple Watch App ver 9.2 (20S361) / Network Provider EE53.0, EE Wi-fi Call.

On the iPhone that the Apple Watch Ultra is paired with, make sure that Settings / Mobile Data / EE Wi-fi Calling / Wi-fi Calling on this iPhone is ENABLED and Add Wi-fi Calling for Other Devices is DISABLED.

During setup in the Apple Watch App on the iPhone select Mobile Data. You will be directed to login to your EE account, sign up to the £7 (30 day) contract and informed that the service will take up to 4 hours to activate. I rebooted my iPhone and Apple Watch Ultra during this time.

You can check the contract is setup on EE website.

To confirm activation on the Apple Watch Ultra swipe up to see the connection data icon next to the Bluetooth icon. It will be green until it is activated when it will turn white. Test the connectivity by shutting down your iPhone and making calls and sending texts.

Nb. If you don’t disable Wi-fi calling for other devices you won’t be able to progress on the Mobile Data button in the Apple Watch App!

Also take note that the model number of the Apple Watch Ultra for it to work in UK is A2684. For US it’s A2622 and for China it’s A2859

Hope this is useful and saves a few hours of your valuable time.