Sorry, I checked once again it was indeed my relatives calling from a different number. I'm assuming it's a telephone booth in Vietnam.

My apologies.

This number called me this morning 5 times and left no voicemail.
I didn't' know the number so I didn't pick up.
At first I thought it was a call from Vietnam from my relatives, but then I checked with my mom and it wasn't.
Then I checked online for the area code and it's none-existent.
So I came here and found there are various numbers that has the same area code.
So now i'm glad I didn't pick up, but I just don't understand how they have my number...