(soft guitar music) - so my name's andy stevens. i'm an electrical engineer. i attended mit and columbia. i get a phone call out of the blue. and he said, i have some tapes that were from a voice recorder. he explained that he had taken these tapes to a couple of different outfits and nobody had been able to replay the tapes. - [narrator] rick had the machine shipped to andy's lab and he immediately got to work. he began by recovering the data on the damaged magnetic tapes with hopes of retrieving the lost calls. - so this is an eyretel media store recorder. and it would record onto these tapes. this is what's called a dds3 data tape, and it will hold several thousand hours of recorded audio. recorded telephone quality audio. - [narrator] the machine was commonly installed in wall street banks, specifically on trading room floors.