They're Accounts Receivable Management, a collection agency.
http://www.mrsbpo.com/
I've dealt with them before. I'm not in debt, but I'm in a major city and we're listed (unfortunately) and have a common surname. My mother did that to save money, and I'm told by now it's all over the internet and no use unlisting it. It really wasn't a problem until about 4 years ago or so. I first did the things it said to do here--sent them a request for debt verification and demand not to call certified mail, return receipt requested. Followed up by reporting them to the Federal Trade Commission, my state's Attorney General Office and my city's Department of Consumer Affairs.
And you know what? It stopped for some months, and then I'm on the database again because they're looking for someone else with our listed first initial and surname. And there are hundreds of these low-life collection agencies, so just stopping some doesn't stop a half dozen calls a day from them, mostly without even leaving messages. Unless you have unlimited call blocking, there's just nothing to do but tolerate these calls, and I'm just glad I have caller ID and an answering machine to be able to do so.
If you have debts, by all means pay them, and to make sure you're not a victim of identity theft, I've found it's wise to at least yearly check your credit report. But I've found the only way to deal with these people otherwise if you don't owe is to ignore them, because it takes way too much stress and energy to try to get them to stop calling, and most of them are too dangerously fraudulent to ever, ever give them any information over the phone trying to clear things up.
If you are in debt, I'd deal with the original creditor if you can, or at least find out from them which credit agency has been assigned the debt, and then deal with them in writing.
I have received calls from this number,MRS BPO LLC, no messege, nothing.
Probably a collection agency, but I'm not aware for what. Soooo, since they will
not state their "business" I will not reply. (My bills are all current.)