Thanks, Derrick. In my case, the LANB is programmed with an IP from the block of external IPs my customer got from FiOS years ago. Now if someone at FiOS assigned that same block to another customer a week ago (assuming the FiOS system will even let them do that), I would think the system would detect that pretty quickly. But as screwy as this problem is, I don't feel like I can rule anything out right now.
A network-related thought I had was there might be an app on the internet somewhere that sends a packet every hour, and the person who set up that app fat-fingered the destination IP address, and now my LANB card is getting it, and the packet messes up the LANB card. But I discounted that idea because of the IP phones coming back to life on their own 10 minutes later. One mystery packet coming in from the internet and screwing up the card I can easily see. But a second one coming in 10 minutes later and resetting the phones, that's pushing it.
I was hoping some LANB expert would chime in and say, "oh yea, the LANB cards have a timer built in that can sometimes turn itself on and run amok." Absent such a chime, I'll probably stick the LANB card behind a firewall. My recollection is that Vodavi equipment didn't work reliably with port forwarding, but it was okay with 1:1 NATing, so I'll set that up. I'll also block all ports except the VoIP ports. Maybe I'll get lucky and the problem will go away. If that doesn't do it, then it's time for Wireshark.
