This number has called me 7 times today, starting at 1:00pm until 9:00pm. No answer when called back. Unknown purpose.

called me while I was at work.....not cool
They answer Home Security Promotions when they are called back....how did they get my unlisted and private number?

They call me at least once a month. I picked up once, and they were asking for personal information. I hung up immediately and have never answered another one of their calls since. I don't know how they got my number.

Do not answer this number - simply block it.
This is one of the security companies that promises a free home security system.
I told the woman I already had one and she said "Our System is better" She then got a boat horn in her ear.
Needles to say she hung up.

NOTE:  Folks, just because you have an UNLISTED or UNPUBLISHED number means NOTHING!

What they do is input into a dialer the NPA (Area Code) and NXX (Exchange) and call from 0000-9999.
That is how they are calling you.  Is this legal?  No it's not, but when they hide behind a disconnected number and use VOIP and call from outside the USA, the only thing you can do it look at 800notes.com and block those numbers that are on here.