A creditor is required to send you official notification (ie "a dunning letter") within 5 days of their initial contact with you. If you receive this notification you will be able to determine who the OC is and determine if this is an old account of yours.
While you will be able to see if this is an old account, the fact that it is from 1997 would indicate that the collection agency is probably a JDB attempting to collect on very old debts.
The SOL may have expired (length is dependent on what state you live in) and it is beyond the reporting period of 7.5 years, so it will probably not show up on any of your credit reports.
I would wait and see if they send you a dunning notice. If it should happen to appear on a credit report, they are in violation and all you would need to do is send a written letter to the CA informing them of the legal reporting period according to the FRCA and they will be obligated to delete it.
Getting phone calls from unknown creditors/collection agencies can be alarming. It is best not to provide any information and avoid any possible admission of the debt until the written notice is received.
Hopefully this will fade away without much effort on your part.
Good luck ---
Starting Score: 696