Hey y'all! I am a total noob when it comes to low voltage work and am trying to help my dad with his phone system. We are a small family owned hardware store. We have had this phone system for about 15 years and this is the first time we've had an issue like this. It is an iDCS 100. We have 5 telephone lines. We have VOIP thru comcast, they have already came and verified it is not an issue on their end.
Yesterday we had a power outage that lasted 10-15 seconds. Once the power returned, our phones no longer functioned properly. From my research, I believe they have defaulted to their original settings. The stations no longer have a name displayed, they say "2xx". I cannot dial out on line 1 but i can on other lines by pressing 0 first. The overhead page functions / intercom functions do not work as they used to. None of that is as big of a problem as the fact that I cannot get customer phone calls. When they call my main line, it says this user has a voicemail that has not been set up and hangs up. They can call my other lines and our phones ring but they are very static-y. Currently I have my main number set to port to my cell phone so I am not missing calls.

I have tried resetting the KSU and nothing happened. My thought, and again, this is just me trying to figure this out, is that maybe because the settings all defaulted, it completely lost the programming and maybe it has something to do with that country code that needs to be programmed in? I can hook a phone into the wall in the unit by the KSU and still cannot dial out on our "line 1". I can dial out on line 3.

I hope someone may be able to give me some guidance! The person who installed the phone system passed away and his company is no longer in business

here are some images:: https://imgur.com/a/qOZ28oZ

thank you in advance for any and all suggestions!