Not all statutes of limitation are the same - some states are a few years, others as long as 15 years. It's a moot point, since these callers are debt scammers who can't prove that anyone owes them money. More information at the link below (from the FTC):
Received exact same call for my daughter-in-law with exception of case number. She took out one of those payday loans over six years ago. She paid it off and had to jump through hoops to prove it. She has been getting these harassing calls from various numbers ever since then. At some point, because she may have listed me as a reference or because she lived with us for a short period of time, I get all these spam calls. Sometimes message is that if she does not call them within two hours someone will show up at the door with a warrant for her arrest. Hasn't happened yet! I can only block 20 numbers at a time on my home phone. I badly need an upgrade!
message stating that they have a case against me such bull crap i filed bankruptcy and all my past debt was discharged so there is nothing they can say i owe to anyone i blocked the number