Collectors routinely phone anyone in the country with the same name as the one on the debt without checking to make sure it's the person who owes the money. So as soon as you get that cold call, ask for the collector's name and address—and then hang up. By law you have 30 days to write to the agency and ask for verification that the debt is yours. Send your letter registered mail or, if you're faxing, go to a store that will give you a dated, time-stamped receipt, such as Office Depot or Staples. The collector must send you the name and address of the company to which the money is owed, as well as notify you of your right to dispute the claim in part or in full. If the debt isn't yours, the agency must cease collection efforts altogether.