I called them back from a land line. It is a collection agency for credit card accounts. I told them that calling me from a land line was burning up my minutes and I was contacting my cell phone company and finding out just how many minutes they had used and then I was sending them a bill. By the way, I do not have any accounts with them and I told them so. They took my cell phone # and said they would stop the calls. They'll either quit calling or they'll intensify their efforts. I guess we'll soon see. I would advise calling them from a land line and telling them you're going to send them a bill for using your minutes. When you get to the automated system, don't enter anything and it will take you to a customer service rep. It will take a few minutes but just wait it out. Maybe if we all start calling the nuisance callers back from our land lines they will stop calling our cells.