Keep getting calls from this number.

It was a prerecorded message from a home security agency that has called with other numbers

Don't know who, what or where.  The number rings in, doesn't have a Caller ID show up, hangs up and leaves no message in my Voice Mail.  I don't know who the number belongs to, but, since I don't recognize it as a number I am familiar with, I don't answer it.  No message, no call back.
This happens a good 2 times a week.

I got a call from this number while at work.  No msg left on my vm.

Same as Rose in CT: I got a call from this number while at work.  No msg left on my vm.