I have some locations out in the dinghy weeds best described as harsh environments. Tremendously high amount of dust, enough to clog the fans and cause them to freeze up in 6-12 months of exposure, and at which point the inside of the chassis looks like it's caked with mud. Also frequent power outages, some lasting several hours, long past the run time of anything short of a hyper-expensive carrier class UPS. Then you provision with a 6-hour backup system and go out to the site the next time they're "down again" after only 30 minutes and discover a coffee pot plugged into it.
These rural users aren't accustomed to "modern phone systems" and are even less receptive to them, especially when what they had was working and what you've given them isn't. I was as happy as anyone else to see the old iron go away, but those systems would only lose the lamps & hold features when the power went out, but with VOIP they're S.O.L. unless we talk them into getting a backup generator....which of course then needs fuel and periodic maintenance all its own.
Just venting...