This is curious as the FDCPA is very explicit.
§ 809 of the FDCPA
(b) If the consumer notifies the debt collector in writing within the thirty-day period described in subsection (a) that the debt, or any portion thereof, is disputed, or that the consumer requests the name and address of the original creditor, the debt collector shall cease collection of the debt, or any disputed portion thereof, until the debt collector obtains verification of the debt or any copy of a judgment, or the name and address of the original creditor, and a copy of such verification or judgment, or name and address of the original creditor, is mailed to the consumer by the debt collector.
The case that really bears worth watching is Guerrero v. RJM Acquisitions LLC, Ninth U.S. Circuit Court of Appeals, opinion 05-15121. When an opinion is rendered, it could spell out in black and white exactly what constitutes verification. CAs are deathly affraid of that. Form letters that state name, address, OC name, amount owed won't cut it.