Who called from 2102490540

I had call this morning from the number everyone mentioned. My question is how do they get the number when is invisible on Facebook? I am glad I had nothing on my account when I called back!

They use a procedure known as  "sequential dialling".   They start at XXXXX 001, then go on to XXXXX 002, and so on.  If a number is not in use, they just go on to the next one until eventually someone answers.  In some con-trick countries, and you know which ones I mean, they use sheets of paper with all the potential numbers written out on them, including notes for when to call back those numbers which ring but are not answered at the time.  In other countries they use software to generate both the numbers and the calls - in fact they call three or four numbers at the same time and speak to whichever one answers first.  This saves the caller's time, i.e. it increases the number of people they have time to talk to each day, and also explains why you get ghost calls, i.e. your number rings but there is no-one there.   I work at home and I have four separate telephone lines and two mobiles.  This means I get a fair number of theses calls.  I have found the most effective way to deal with them is to clamly and politely say  "Oh hello, would you mind holding on ?"  They almost always say yes and then I just put the phone on a desk, shelf, filing cabinet, etc. and get on with my work.  They want to waste your time, so waste theirs instead.

That's the best way of dealing with them as the software blocks your call.
My Ex worked in a magazine call centre and they had to deal with subscription issues in an allotted time.
If they took longer the computer flagged the calls and usually blocked them.

I thought that if you replying to an international number this call will cost the receiver as well as the sender. Am I right? Otherwise this is great idea to stop them from calling again

I've got several calls, tried calling it back, no answer