[mindfrost82]

If T-Mobile does the same thing as At&t, then everything is run at Half Rate codecs on EDGE. The phone does seem to make a difference though. With At&t, I've had some phones sound horrible on EDGE, and some sound really clear.

If T-Mobile uses 3G for voice like At&t does, then the calls should sound a lot clearer while using 3G compared to EDGE. The calls on At&t 3G are so much better than EDGE, its like night and day. Of course, if you're in an overloaded iPhone area like NYC, then At&t is known to be bad, but from what I've read, they've spent lots of money improving their network there over the past few months.

At&t has been good for me the past year that I've had them. Now that I have good 3G coverage, call clarity has been on-par with Sprint, but I'm also not in a heavily populated area.