I have tried all those combinations, yes… I have come to the conclusion that even though there’s a separate field asking what country you are a citizen of, I think it’s expecting an actual US number to be input, i.e. It’s an *internal* type form, not to be used with UK numbers…..so that would explain why it was impossible! ….it won’t/can’t validate the entry!
I have registered with Twitter as I found they had a Twitter account, so have tweeted them…..am sure it will resolve itself! Fingers crossed!