There are some other weird things going on, which may or may not have been occurring before the meltdown.
When one phone in the initial ring group is answered, on of the other phones keeps on ringing.
On another phone, there is a multi-second delay between picking up the handset and the call connecting to the inbound call.
I've also noticed that when I call inbound to test with my cell phone, answer one of the phones on the initial ring group, then hang up the handset . . . the call does not disconnect on the cell.
Again, these conditions may have existed prior to this morning's meltdown, but I can't be sure.