I ran into a recent issue and thought I'd post it for others.
With our soon to be gone POTS line we never had callerid. Now that we do have it with the OBi, we noticed that the time stamp was off by 3 hours. I reset my portable telephone system's base, wondering why it was wrong, then later that day noticed it was wrong again. Reset it again, and again later it was off.
I checked in the OBi settings and saw that under System Management > Network Settings there is a Local Time Zone which defaults to Pacific Time. I unchecked the default box and changed to East Coast Time, and now a full day has gone by where the time stamp is correct.
So, the OBi was somehow providing my portable telephone system with a time sync and resetting the machine. Or, I have gremlins that never did this before I got my OBi. While we didn't use callerid before, we did get messages and they had the proper time.