ACS phone calls

Well as best as I can tell, this business is located in Philadelphia, PA. For months my wife and I have received phone calls from this company at different times of the day. We are registered on the no call list in Colorado, but it doesn't seem to help. We always get telemarketer calls. Years ago I was a telemarketer for a month (hated it, very scummy people for the most part). The thing you can do to hurt them the most usually, is to keep them on the line and don't buy anything. Anyway, ACS has called about 20-30 times, and there usually isn't anyone on the other line, I think its an automated system to check when your home. However, this time I got an actual person and she was asking me if I knew some people and if I could "deliver an urgent message". I didn't know the people she mentioned and told her so. I found it very odd that a company would call and ask for someone they don't even know to deliver a "urgent message". Anyway, she seemed annoyed that I couldn't deliver this "urgent message", so I aked her what the message was and maybe I'de be able to figure out who it pertained to, perhaps I hadn't thought of someone. She refused, but I asked her if she couldn't give me the message, then why was she calling complete strangers to deliver "urgent messages". She had know answers and hung up. I looked up the number as soon as the call was over and read several complaints. It sounds like a collection agency or something along those lines, but may be just another phone scam. I do wish I could block this number but nothing seems to keep them away.