Write the lawyer back and ask him. Take a conciliatory approach like "I'd be happy to pay off this debt if I had the details to help me ascertain its validity..." You could also ignore it and wait until you get sued but this is dangerous as some unscrupulous lawyers take advantage of consumers in situations like this. You may know nothing about the suit until you get notice of the judgment. Of course you can then contest the validity of the judgment but it would be easier to negotiate a solution to this before suit is filed.
Under the Fair Debt Collection Practices Act, any letter to collect a debt should identify the debt. You should write back immediately, and include the words "I dispute this debt." I would not make any offer to settle, since technically, that could have the effect of reinstating a debt that otherwise lapsed due to the statute of limitations (you actually have to make a payment to reinstate, but they might try to argue that a letter with offer language in it was an admission of some kind). You have 30 days to dispute the debt in writing, so I urge you to act quickly.
Many lawyers are interested in helping people whose consumer rights have been violated. You can find a good list of them at the website for the National Association of Consumer Lawyers, or here on Avvo.
I just wanted to add that Dodeka LLC is well-known debt collection agency. Any list of judgment creditors, particularly in Texas and Florida will include Dodeka llc. As they are professional debt collectors, the previous answer is directly on point. Just dispute the debt. Always remember that when you talk or communicate with a debt collector in any way, they may be able to use everything that you tell them in any action brought against you.
I agree with Ms. Crocker & Mr. Michelin. I will add several points. First, in my experience, dealing with debt collectors by telephone usually gets you nowhere, and often just increases your stress level. Second, whenever you write to a debt collector, it is a good idea to send your letter by certified mail, return receipt requested, and keep copies of what you sent. You may want to enclose a copy of the collector's (or lawyer's) letter, so that they can easily identify the account and can't claim later that they did not know which account you were referring to. Also, keep the return receipt.
I also encourage you to consult with a consumer attorney in Ohio, especially if you receive any notice from a court.