Also, make sure that it was an actual law firm that called. The first time Il-Legal Mediation Mal-Practice contacted me, they used those exact same words: there was a case against me filed at their firm.
LMP was no more a law firm than I'm Britney Spears.
And I would do exactly as GoldenBast suggested, DV every CA that contacts you. Make sure the amount of the debt they are trying to collect on is correct and they are even authorized to be collecting on that debt.
As for the "failure to comply" comment? If I had a dollar for ever CA that told me they were going to mark me down as "refused to pay" when I was unemployed and had no money to pay, or some other such nonsense, I would have been able to pay back all my debts. And then some.
I told one CA, when they threatened me with that, they could mark it down as me telling them to kiss my @$$ for all I care!
Also, check your state laws regarding any laws that do apply to the original creditor. The fdcpa only applies to CA's; however, your state may have laws in place that are applied to OC's.
Florida (my state) has the "Fair Consumer Collection Practices Act" and reads a great deal similar to the FDPCA and is applied to OC's as well as CA's.