An interesting post from my friend, Doug, in dealing with debt collectors.
When you receive any subpoena….Be very proactive, go on attack, so no wait.

1. Respond but carefully..
2. Don't volunteer anything (you usually do without knowing it by your actions).
3. Answer honestly (but do so with wisdom).

For example say: I assume this is about a debt collector, be it a tax issue, lawsuit, collection attorney matter, mortgages, traffic tickets, and more. It is all fundamentally the SAME issue. 

It is not YOUR job to validate anything or verify their claim, it is always the duty of the charging party to prove everything. You will be surprised how often they cant do that. They usually reply on you to confess by your actions, or lack thereof. 

Your general position is: I am willing to pay, and am making a promise to pay any verified amount, upon fulfillment of the Fair Debt Collection Practices act. That is to say, they must swear under penalty of perjury, that I owe this allege debt via personal first-hand knowledge of the one man or woman who claims I owe it.

It is presumed by you that no valid contact exists between you and this entity, and that in fact they are harassing, threatening, using intimidation tactics to extort funds that you do not owe. Bring forth here and now, someone that will fulfill the only requirement I have made, or charge them with criminal intent, OR even have them pay me $3,000 for harassment, wasted time, intimidation, false law suit, extortion, and change them with criminal intent for the same and mail fraud.

Then after you default them out for not responding fully (and you create a record of your bills and for their effective non-response.  Then sue for damages in Small Claims, and collect your $3,000, after they fail to respond to your bill. This becomes the basis for you Small Claims suit. Very likely they will leave you alone after you do this. No contact equals no liability.  Always give them due process fairly.

They will very likely never want to hear from you again. But follow through is key or they will roll over you.