So here's my weird situation:
I called care and after I told them that there are other users in the Bay Area having issues, they still determined on their end that it's my device and pretty much established a warrany exchange. This only because if I switched my sim card over to another device, the other device would fully camp on versus if I put another sim card in my original device, the device would not camp on.
Now later on, I went from Hercules to Walnut Creek and tried to see if my original device would work. Guess what? It did. When I got back home to Hercules a few hours later, my device no longer worked.
So I called Business end user care (since I'm on a foundation account) and explained everything to the rep. He told me there was a trouble ticket open for certain towers in the Bay Area and there was no ETA for resolution. He said the issue was a congestion issue and they were trying to get more trunks put on the towers. I told him it was close to 1AM and there's no way that it's a congestion problem, plus the fact that I can use other devices with my sim card and those devices can camp on to this particular tower in Hercules.
My take on this whole thing: Certain towers are not allowing devices within a certain IMEI range to camp on the network.
The rep advised me to continue with the warranty exchange for the time being and wait 24 hours to see if my original device will operate back to normal.
If it weren't for the fact I have spare devices, I would be pulling hairs right now!
So I'm now temporarily using my Sony Ericsson T68i. The phone was state of the art three years ago! The monophonic ringtone of Violent Femmes's "Blister of the Sun" which dates back to when I got my first cell phone (Nokia 8260/TDMA) back in 2001, is still on the T68i. It's so weird not having a device that has a polyphonic ringtone!