losing cell network
 

I've been randomly losing my connection to the cell network for 30 minutes on end while my phone is idle in my pocket. The signal strength icon and the "operator name" (T-Mobile) disappear, and I don't get incoming calls or SMS at all (people complain they couldn't reach me). I've had it happen twice in the same area, but I've never seen it happen using the same SIM in the same area with my old phone (this is at ground level in downtown Indianapolis, not out in the sticks).

So I'm wondering what I can do to catch it and troubleshoot when it happens again. Is there some logging or debug info I can enable?