I have this same problem on my elderly and vulnerable father's phone. He just gets paper bills so I cannot login to an account to check it that way, as an email has never been set up.
He and my mother cannot make any outgoing calls, they just get the message 'you need to reactivate your phone number'.
Landline number is in my profile details.
They are in their 80's so I need to sort this out for them.
Have just sent you a Private message with info on how to help progress this.
Stephen, Community Manager
Please log in to My Account if you need to view or pay your bill, manage boosts and track your usage. From My Account you can also check your connection and test your line for any issues in the Service Centre.