'Manage this order with Apple ID' issue

[Jason Davies]

Hi folks,

I ordered some Airtags and got a link, and it offered to add the order
to my Apple ID. So I did, then it asked for the phone number I used to
place my order.

But no matter how I enter it (a mobile number) it says 'Please enter a
valid phone number using only numbers.' I've typed it in three times,
copied and pasted, removed the 0 and tried to add +44, all to no avail
(nb it says 'Please enter a valid phone number using only numbers' not
'this is not the number we have on record).

Anyone know what Apple consider a 'real' phone number?

Cheers,

Jason