The idea behind many cheap phone systems is to get rid of the installer and service person.
Guy buys on internet or at the drug store, I don't care. If they can install and set up fine.
But when a problem pops up and the customer needs to be doing HIS business instead of learning how to trouble shoot phone systems and lines, now they call to find someone to help.
Guess what, not many phone techs know squat about this system, because there is no INCENTIVE to learn.
(you can't make any money selling, and on that cheap end of the market none servicing it.)
You can't know every system. I won't waste my time learning a system hat has no income potential.
Yes, if I had nothing to do I might go work on one
if I had a manual. But I would be in the same boat as the owner, shooting in the dark learning a new system.
So if he gets help, he's like a letter without a Zip Code.