rings phone twice and hangs up

I got a call around  6:46 pm but I didn't get a message or nothing.
 who are they?!

please post

I got a call around 6: 00 pm but I did't get a message or nothing . and again around 6 :30 pm .
Yes .  who  are they ?

I got many calls yesterday from this number, no one ever answers and when I dialed the number back no one answers and it has some service repair and asks some questions. I know I'm getting tired of the phone calls.

I got call twice this morning. No answers.