There is a similar scam alert from someone who shared his/her story here too. Its exactly the same.

I received a call from a number 8057 6284 (+65 prefix was not present). The caller was a male and spoke in Mandarin with a Malaysian accent. He started by saying that he changed his handphone number so his purpose of the call is to update me about it. Then i know who is he. He said you guess la. i replied no, i don’t know. He said u think harder la. i repeated at least 2 times that i really don’t know who are you, and maybe he called the wrong number. Again, He REMAINED INSISTENT THAT WE KNEW EACH OTHER and went on saying YOU DON'T REMEMBER? We always talked on the phone one! You think harder la! Throughout the call, HE REFUSED TO REVEAL HIS NAME AND KEPT PROMPTING ME TO GUESS and guess.

i refused to give him any name after umpteen times of “you guess who am i la, you think harder, we speak before.” so he said “i have another incoming call” and he hung up immediately.