I was dispatched to a nursing home yesterday with a report that the receptionist phone was not working due to a bad jack/wiring. Upon arrival, I find that there is nothing wrong with the wiring. The phone works fine, but it appears to have some kind of restriction or feature enabled that is preventing it from making any calls.

The feature keys for line 1 and line 2 are lit up red. They are idle on all other extensions, and all other extensions can use line 1 and line 2 just fine without any issue. I have worked on DSX, SL1100 and SL2100 but never a SV9100. I told them they would have to contact whomever installed/programmed the system, but they have no clue who that would be. There is no identifying information on the system itself nor any documentation that anyone can find that may identify who installed it.

Does this sound like a simple feature that was enabled by mistake?

You would need to look at the programming. What trunking are they using? Are they using CAP key, lines keys or loop? Are they restricted? Hit Feature 3 on any phone and get the hardware code. NTAC should have that info for the installing company. Don't know if they will help a non SV9100 certified tech though. A LOT of nursing homes were put in by nationals. There has to be documentation or a bill they can trace back to. If you have a database backup you can get the password from that. Otherwise you can try some of passwords. Chances are they are all changed.

Best I can tell, is that they are line keys and they are using analog POTS trunks. I don't have a database backup as I don't work on these systems, and I doubt the employees on site have any idea if there is one available or not. Never thought of contacting NTAC. But beings I'm not SV9100 certified, may be a moot point.

If you go back to this site, things to try, re-boot the phone, pull the trunk blade away from the back plan and reinstall, if these fail power cycle the SV9100 (your call if no data base backup) memory is nonvolatile but there is always murphy's law.

Contact NTAC, like Coral Tech said they can look up the hardware key code and see what dealer had been assign. I see no reason why they wouldn't help you with this, NEC doesn't like hearing from unhappy customers.

Regarding pulling the trunk blade, I believe this solved the same problem I ran into 5 or 6 years ago, but I'm not 100 percent sure. (it's that age thing)

Good luck!

Beings this is the only extension that is behaving this way, do you think pulling and reseating the trunk blade will have any affect? The lines work fine on all of the other extensions. I did not reboot the system, as I'm not sure of the "proper" restart procedure - short of pulling the plug.

I didn't read your question fully, I thought all phones were locked out of lines 1 & 2
Power it down via the rocker switch on the front left side, wait for status LEDS to go off, count to 20, power back on.

Will try the restart procedure and see if anything changes. Thank you for the information.