@ZogG Ok a friend of mine just tried to register using my phone number, however the registration also failed on his mobile. He tried his own number and it seemed to be working fine.

I am somehow getting the impression that my number has been blocked by Whatsapp.. Do you think that is possible?

Anyway, I have sent an email to support@whatsapp.com to ask about it.

If anyone has ANY idea how to resolve this, please!

Cheers!