I researched this a bit and it is definitely MRS Associates.  They have offices in Phoenix, AZ - Cherry Hill, NJ and New Albany, OH

They use a cell phone # in Illinois (224)-588-8816 and other #'s from various states.

Here's a link to a website and forum that's done more research than I have done.  Just copy and paste it into the address bar.  They don't seem to have a good track record with dealing with the people they are going after.  The site lists many steps that can be taken to get them to leave you alone or atleast deal with you on the level and with respect.

http://www.debtconsolidationcare.com/forums/mrs-associates.html

Remember, these people cannot have you arrested.  They could file a civil lawsuit to collect a debt but then you get a lawyer (or do it yourself if you are able) to have them produce all records/documentation and chances are really good that they don't have them and it will be "Dismissed without Prejudice".  Then it's a matter of Statute of Limitations in your state until the debt can no longer be legally collected.  We should all strive to make good on our debts because it's important for the individual and the society but DO NOT FEAR THESE PEOPLE, ESPECIALLY IN THIS DAY AND AGE OF MASSIVE DEBT AND CORPORATE/GOVERNMENT ROBBERY!

See http://800notes.com/Phone.aspx/1-877-774-7997

MRS ASSOCIATES, INC., Collection Agency
3 Executive Campus, Suite 400
Cherry Hill, NJ 08002

Phone Number:
(877) 774-7994
(877) 774-7997
http://www.mrsassociates.com