I hate to ask. We are a phone dealer, but I have had very limited experience with this PBX. I have worked on the KX-TD1232 and KX-TA824 and even went to a class for Panasonic Kx-ns700g after Toshiba went under.
A new customer can't find a local Panasonic dealer in the area (Orange County, CA). So We thought we would see what we could do to help.

I haven't been on site yet, but the customer says they have a KX-TDA100 with TVS125.
Symptoms: DDS console is not working properly, we are unable to put our phones on “night mode” while we’re not in the office, we can’t check voicemails, and one of our phone lines is down.