NCO is a collection agency. Many people believe the do not call registry covers collection agencies.... It doesn't, they are calling because you either have an account in collections or you have a phone number that was once registered to someone that they have in their system.
They call me 6 times a day and I have only missed one payment and it is 10 days late. I talked to them and said I would pay it this Friday and they still won't stop calling.