In my previous job as a telecoms technician maintaining business telephone systems I found fax machines were more trouble than all other pieces of telecoms equipment put together. It's generally okay if connected directly to a PSTN line but if connected through a PBX some brands didn't seem to work reliably with some brands of phone system.
It seemed that every business felt the need to have one (and some had dozens of the things for different departments) yet I could tell from looking at the call records from the line provider and the traces from the telephone systems themselves that most were rarely used. The one in my office generally only got used when I sent a test fax to a customer who was reporting problems with theirs!
About six months before I finished in that a job, a customer was making changes to their telephones and changing from ISDN to SIPs and a screwup at our end meant the customer's fax line (which was a standalone analogue PSTN line) accidentally got cancelled. We only noticed this about a week later when the paperwork came through. There was a lengthy delay of some weeks trying to get the line provider to re-connect the line and retrieve the original phone number (which is obviously important as the end user has probably put it on business cards, ads etc). Our manager decided we wouldn't tell the customer and would act stupid and blame a line fault when they reported the fault. Every day I waited for the dreaded phone call saying their fax line was dead. It never came! Obviously nobody had tried to send a fax and it was never noticed which shows how pointless paying the line rental and maintaining the machine actually was....the customer in question was actually a company of solicitors, the sort of business I thought might still have use for a fax machine but obviously not....
