Marie you are exactly right. Someone calls me from the UK on a cell phone and each time she calls it is this same number 774 436-9900 showing up on my caller id, which is not at all her cell phone number. Must be some sort of calling card that she routes the calls through to pay less money to call the US.
Yes, it is a discount calling service from the UK. We have them here as well (like cloncom, etc.). For the most part, they are legitimate incoming calls from someone using their discount calling service.