This is awesome. Using computers for what they're best at: fax and figures.
I'm curious why this requires a reply number in the program, rather than relying on something like Caller ID and sending the reply back to the number that sent the fax.
It was probably just easier to implement. The build script[1] already has the source code, extracting the number from a comment is trivial, while retrieving out-of-band data like Caller ID from the fax server is likely more complicated. For a joke it's not compelling to do that, especially if you've already been fighting the fax server...[2]
I'm curious why this requires a reply number in the program, rather than relying on something like Caller ID and sending the reply back to the number that sent the fax.