Fax wiretapping
A discussion came up about the common claim that "Fax is insecure", but nobody could initially find actual evidence of it or a way for a mere mortal to turn an audio recording of a fax transmission into the image that was sent using publicly available tools, only "talk to our representative" enterprise solutions that might implement decoders.
A litte search subsequently revealed this page that suggested using the fax_decode program from the the spandsp library from the soft-switch project could work and was reported functional using test audio files, those however had the transmit and receive channels separated and only the transmit channel was fed to the program. That's not how a wiretap would come out (both are mixed), so having the needed equipment to run a test it seemed like a fun morning project.
A test setup was made with my fax-capable MFP connected to a Cisco SPA122 ATA that is set to be able to dial to another one connected to a Windows XP laptop with built-in modem running the Windows fax console. Faxing from the MFP to the PC (and vice versa) was known to work correctly from previous endeavors.
The phone line cable between the PC and ATA was cut and a very crude tap was made using a 220nF capacitor from each line and fed into a Zoom H6 audio recorder