"According to Wikipedia, Straight Talk is on AT&T's GSM network only. IOW, no 3G."
Thats what we get for using Wikipedia. This is not true unless Edge now provides .9 - 1.8Mbps. This is what I'm getting, though on an LG C900.
This does not clarify for the Nokia, but clearly MVNO agreement with Straight Talk is indeed NOT religated to Edge, and I've not dropped below .6Mbps which is still above EDGE. Also, occasionally I will get 8 and 9Mbps for a good 5 - 10 seconds (before the Master Switch figures it out?).
This is a question of Frequency. If you have one of the ATT 3G freqs in your phone, your good to go at least at the HSDPA, I dont think Im getting HSUPA, and the HSPA+ is only a matter of time in my opinion. New to ATT so don't remember the freqs, 800/1700/2100???