Unable to send code. Why?

Ok so I tried to change my billing method to mobile phone billing and even if the number is accepted it says that;

'Unable to send code.We cannot complete your request at this time. Please try again later.'

And I tried 'later' and it was the same. I wonder why? I don't know what to do. I tried to change it from both iTunes and Appstore and from Payment and Shipping and it's the same result. Can someone help me please?