Faxes took about 45 seconds per page. I think this particular bug could have been resolved with a 90 second phone conversation. The fax cost savings were small, but still a neat story.
You can't always get on a phone call, time zones exist :)
(Also, not all fax debug stories are done in 45 seconds. I gotta see if I can find my old faxes - fixing a "stop shipping" bug in a video game via a series of back-and-forth faxes from a cruise ship. :)
It would be best to do both. Does anyone do a screen share to diagnose a problem where they don't talk as well?