I received a call from viber, his account name is duty free. He told me that i won $50,000 from Changi airport. He confirmed my mobile number and the first 8 digit number of my atm. Next is he wants to have a video conversation and he is asking to take a video of the atm card. I doubted that i won the lucky draw and he keeps on insisting on it. He called again 4 times after I dropped the call.