I have only seen programing change on it's own in a couple rare, isolated instances. It appeared that some of the most recent programing changes reverted back after a power outage. In those cases I believe what happened is that the last changes were not backed up to the SD card and the system reverted to the older database after a power outage.

In almost every other case when something seems to have changed on it's own or the system is acting weird, I usually find an actual reason. That's why trying the Night key was the obvious first step. I see DND and Night keys toggled all the time, and sometimes the users didn't even know what the buttons were supposed to do.

I don't believe a power cycle would fix the ringing issue, but I doubt if it would hurt anything to try. Like any electronic appliance the Toshiba PBX can have it's minor quirks, but overall it is a very stable system.

I am assuming that by now you have already reset the PBX. The next step would be to start with the Trunks DIT settings to see how Day 1 is set for those lines.

David
Tele Express Business Systems