Lisa thanks. It seems that I've missed Mike's answer, sorry about that.
However, IMO he only provides a partial answer. Do the overseas customers also get a (celular)phone call? Implicitly, based on Mike's reaction I'd conclude that the answer is yes, but is it actually the case?
BTW, do PAYPAL customers also get verified? If not, that would be a feasible solution it seems
Regards,
Cem