i do have it working but i never used att sim i can have maps running just with network position and it get a fix with few seconds i have unlimited web for dumbphones for 9.99 internet2.voicestream.com

if you go settings, under internet connections, you will get a pop up window, on the right side you have connections, highlight tmobile internet or whatever your connection is named for tmobile, click edit what i have is connection name and type gprs, then when i go next i got access point name internet2.voicestream.com and everything else is blank then you go next, and you have advanced click on it, proxy should not be check and ip should have auto retrieve check, and auto dns check i hope this helps .