Short answer: YES -- but only on AT&T.
Your problem is you are on crappy T-mobile. With the Jelly Bean upgrade your phone is now essentially an "international" Galaxy SIII GSM (Samsung I9300) GSM + LTE (SCH-I535) phone. The "international" version of the SIII does not have the high speed 1700 MHz T-mobile bands, only the AT&T bands.
Samsung Galaxy S III/SCH-I535
http://forum.xda-developers.com/wiki...S_III/SCH-I535 claims your phone supports
- 2G GSM/GPRS/EDGE 850, 900, 1800, 1900 MHz;
- 3G UMTS/HSPA+ (21 Mbps down, 5.76 Mbps up) 850, 1900, 2100 MHz <THIS IS IMPORTANT
- 4G LTE 700, 1700 (AWS) MHz.
T-mobile uses 1700MHz for HSPA+ and uses 850 & 1900 MHz for 2G. (Yes, T-mobile is re-farming some of their 1900MHz spectrum to be HSPA+, but in many areas it's still on the 1700MHz band.) Your phone's GSM capability is NOT on the 1700 Mhz band. So, you get no T-mobile hi-speed data.
But the GOOD news is you will get AT&T hi-speed data! See, the AT&T version of the SIII (SGH-I747) has UMTS:
850, 1900, 2100 MHz
EXACTLY like yours. So you are good to go on AT&T HSPA+. Just get a Straight Talk/Net10 "AT&T" sim card, configure the APN for that network, and fly like the wind.