According to Samsung's own USPROF files, Samsung is preparing a Full HD smartphone for ATT. Rumors surface that the Samsung SGH-I337 could be the next generation Galaxy S device by Samsung, also know as the Samsung Galaxy S IV. Samsung want to announce the next Galaxy S in March. The Galaxy S IV is rumoured to have a 4.99" Super AMOLED FULL HD display, a octa-core processor and a 13 megapixel camera. The phone will run on Android 4.2 called Jelly Bean.
According to Galaxy s IV information in hands from SamMobile Samsung will bring the device to the market in April.
The global version is expected to be part of the GT-I950X model number family and so far we have confirmation that the phone will be not be shown at Mobile World Congress. Whether this is indeed the first Galaxy S IV UAProf sighting is yet to be confirmed but the information so far seems to match the expected/rumored specs.
See above screenshot.