the Statue of Limitations should be up, depending on the state of your residency. It is normally 6 years or so. They can't sue you but it can appear on your credit report, but since it is so old, that may have been removed as well. If they call back, tell them the Statue of Limitations has passed and they legally can't do a thing about it.
Debt never goes away until it is settled or the debtor dies. However, you are correct, it falls off your credit report after 10 years and once the Statute of Limitations has passed, they can no longer use the courts to force payment. But except in a handful of states, legal owners of the debt can still attempt collection but must adhere to the provisions of the Fair Debt Collection Practices Act. Threatening legal action on a time barred debt is a violation and the collector can be sued for $1000 plus court costs and attorney's fees,