I would not put too much emphasis on the 30-day period required by the Fair Debt Collection Practices Act (FDCPA). The statute requires that the debt collector give you 30 days within which to dispute the debt or request certain information. But you are already dealing with an Attorney. They will either sue you or not, at which time you can present all of your defenses (or attempt to settle). It may be helpful for you to dispute the debt, but they will almost certainly not go away.