I have the same problem 9a.m. to 5 p.m. I have no or extremely limited access to data despite 4-5 bars of 3G "coverage" indicated on my iPhone 4s.  My concern is what AT&T is doing to correct the problem?  There is no indication to suggesting remediation is moving forward.  I wonder if we shouldn't be given discounts for our inability to use data for more than 50% of our productive day. Is there a service contract violation here?