Thanks Meter 136
Join Date: Dec 2010
Location: Jacksonville, NC
It's been almost a year since I swapped my SGH-I337 (At&t S4) for my SGH-M919 (T-Mobile S4) but I do remember SIM unlocking and enabling the AWS bands on the At&t phone and testing the 4G with a buddy's sim card. Everything worked fine.
Side note: the SGH-M919 works flawlessly on At&t's network. 4G LTE, MMS, visual voicemail, etc. No issues whatsoever. Hope this helps!
Galaxy S4 | PhilzTouch, Unlocked, CandyKat 1.5.5
Galaxy S2 | PhilzTouch, Unlocked, CandyKat 1.5.5
Transformer Prime | Unlocked, NvFlash, TWRP, CM 11
Nook Tablet | Cyanoboot, TWRP, Rescue SD, CM 11
HP 4540s | Hackintosh, OSX 10.9.3/Windows 8, 1TB, 8GB
iPad 4 Retina | iOS 7.0.4, Jailbroken / Wife's iPhone 5c | Stock
Xbox 360 | LT+FW / PS3 | 4.46 CFW, 1TB / PSP | 6.60 CFW