Sued

What state do you live in? When was the last time you actually made any type of payment toward the account. Check the Statue of Limitations for you state as this debt might fall under this.

If you received a summons, make sure you answer it and make them show proof that you owe THEM the money. Did you have an agreement with them or do they have an agreement from the OC, probably not. They hope you do nothing, that's how they win.

guest is right, they expect defaults. did they say they were going to sue or did you actually get served? you can call superior court to see if they have a judgment against you. did you receive anything in writing from them> did you send them a debt validation?