There may be regulations in the state where you reside that provide further consumer protection.
State laws vary.
Within five working days after you are first contacted, the collection agency must send you a written notification of the amount of the debt and the name of the creditor who referred the debt to the agency. This notice should also inform you of your right to dispute the debt within 30 days of its receipt. Call you at work, unless you inform the collector that your employer prohibits it. Contact you by mail so long as there is no reference to the debt on the envelope. Contact people who aren't directly involved in your debt to get information on where you live and work so, long as it is not a communication about the debt.