Voip.ms UK 03 (Non-Geographic) number reachability

[MZB.]

The Voip.ms premium routing will not handle calls with a +443 prefix (a UK, non-geographic area code prefix). Tech support claim that because it is a non-geographic number: therefore calling it from abroad isn't supposed to work.

(There doesn't seem to be a problem when calling such numbers with voip.ms value routing, as well as from international POTS lines).

I thought UK 03 prefix non-geographic numbers were supposed to be reachable from abroad.

Are they correct? Do I need to use a UK geographic number to ensure reachability from Europe?

Does any other VoIP provider prevent calls to UK 03 numbers?

(Note: the 03 numbers are suppose to be non-premium normal rate geographic numbers, not to be confused with the 08xx numbers).