It looks like a scam number. I tried to call back and it was responded with the message "the number you dialled is not in service".

Just rang and no one spoke I tried calling back and message said number was not in service so just block this number obviously some sort of scam

I got a call they said they called regarding refund things. but I don't have any idea and actually I couldn't understand what they said. so I asked to send an email. then, they just hung out without any answer.

They didnt leave a message. I called back but got message the number is not in setvice. Blocked the number

Scammers