I switched to T-Mobile just in October sometime and the reason I switched is because I had weak coverage at my home and at my work by most providers and then I tried one UMA 8320 from TMO which seems to work at both places.
But ever since Tuesday Dec 04, 2007 I am truly frustrated due to constant interruptions in UMA service. I have opened trouble tickets with their support who said turn around time is 24 to 72 hours, 10 days in some cases.
I may be just a little over 30 days and am seriously considering opting out of contract. With AT&T I could at least get some week signals at my home and at my work but with TMO none