Who called from 7816136500

This number has called me several times, every time saying hello then speaking in Korean or some garble. I ended up Googling the number and ended up here. I've been getting some weird 2000/200-0 numbers that call strangely close to the same time, leaving messages of un-recognizable noise. What's the deal?

Seems like this number may be hacking its way into using our conference bridge & we get the invoice..so beware.

The message left was "Hello, is anyone there?"

It's a calling card...

Uhhh they called me aug. 9th at like 8 30 n just said nuthin... wtf??? i called back and it said the number is disconnected.