USS North Carolina, I assume? A bit awkward using a Japanese phone system in there, huh?

I've got some dual cabinet systems working on -3 software, but they are very problematic after power outages. It is true that both systems must be operating on the same software version.

The only problem I see is that upgrading will take you to the last version that was available (-7). Since you'll likely be jumping multiple version steps, you should consider defaulting the system and starting from scratch.

Are there any Panasonic dealers in your area? It might be worth talking with them before you do anything since Panasonic systems have been known to have a "mind of their own" when it comes to upgrades.

Otherwise, please check back here and we'll do what we can to assist.

Ed Vaughn, MBSWWYPBX