This is one of those scum companies jumping on the newfound 'Old Debt' bandwagon. They buy old, often beyond statute debts for literally pennies on the dollar and then try to squeeze it out of you.
In my case, it's a $28 bill from Columbia house video club from over 5 or 6 years ago.
2nd letter I received from them LESS THAN 30 DAYS after the very first letter I ever got about this (you have 30 days to dispute the debt) was already threatening legal action.
Very shady practices already from them. So far, they call once a day like clockwork at 8am, never leave messages and don't call again.
Best bet with this company is to definitely learn your rights under the Fair Debt Act and your state's statute of limitations on debts. Mine (in IL) is 5 years on open accounts.
If you find whatever they're calling you about is beyond the limitations, tell them to go jump off a cliff.