I belive it's an international scam
some times they call about visa trouble talking in english with acsent. Then other times talking in chinese very fast I,m not chinese so I have no idea what their talking about. The number above was blocked but came back I think one of the digits is different from the number I blocked I have blocked other numbers but they just change number and re-call they wont get any thing from me but it is a pain because they keep calling. and vodaphone cant block them because their number keeps changeing