Well, after a few months of pretty stable data connectivity, the constant drops have returned w/ a vengance here recently. I don't see how replacing the sim card and doing a master reset would resolve the issue. After researching other posts, and seeing Staudie's reply, replacing the sim card doesn't help. I've also tried resetting the phone, w/ no luck. Makes me think its a software problem (which I thought Thunderbolt was due a new software push a while back), or a network problem. Either way, I'm not getting the service I'm paying for.