That's a somewhat vague catch-all message that Apple has started using. It unfortunately does not ell you what is wrong, just that there's something they don't like or is missing.
I don't see that everybody in the world has to have their own unique telephone number, so until I see a statement from Apple saying you absolutely must, the field is still open as to the problem.
Are you using your number as an Apple ID, or an email address? They do appear to require a unique email address for an Apple ID.
For a generic, numeric, vague, or unknown "error" messages I suggest you contact Apple.
Refer to this page for Apple Support features ➔ Contact - Official Apple Support
Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.
This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple for support and service - Apple Support