I have to say im a little upset with ATT in St.Louis.. Im with my buddy and he has the same phone but his is the Tmobile M919 . We ran multiple speedtest and mine with Att averaged between 12-15 mbps .. While my buddies Tmobile gs4 averaged above 25Mbps and with one of his hitting 42mbps .. I have to say i am unlocking my phone and popping a Tmobile sim in next month .. Although my speeds with Att are pretty darn good .They just dont compare .. I guess the real test would be overall coverage .. Has anyone on here used their ATT GS4 with Tmobile? If so did you encounter any problems as far as data connectivity ? I know it will work with Tmobile I just thought i remembered reading a thread where someone was having issues with their LTE staying connected when it should be ..