I have the curve and my coworker has the Pearl. We both turned them off and back on and got a signal. Strange as it affected both of us at the same time until we powered off and on.
Sounds like a provisioning (connection setup) glitch. That can happen randomly if the edge servers hit a software bug - or network hardware is replaced, reset, or browned out.
Hopefully it's because T-Mo is rolling out 3G in the area!!
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8300 Curve: viigo, gmail, google maps, way too many emails/day