T-Mobile coverage is as flakey as Sprint, just different paces, as your neighbors and co-workers how their data coverage is. Personally, you can't get T-mobile inside my house, but a neighborhood 5 miles away, T-mobile is the only data service available.
Tethering and data amounts are also a concern. Straight Talk isn't very straight when it comes to limits. LOT's of people have been burned by their policy. From what I have read, data and tethering on the AT&T side is more strict, however both are not so great.
The general consensus is you can use 100megs per day safely, and a MAX of 1gig per month and if you tether on AT&T side, you may not be there long. They do often send a text message to warn you when you get close to whatever limit they have imposed at the moment, but often it arrives after you break that limit, which gets you suspended. They do not just cut off data, they tend to cut off EVERYTHING. Do it more than twice and there is a good chance you will lose your number and service.
It's called Straight Talk, not Straight Data for a reason.
S-of let's you install kernels and radios. I highly recommend rooting, s-off and doing the "fix everything" sticky. It corrects the messaging issues.
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