The User Agent Profile, UAP of a device had been revealed. The smartphone had not been yet officially announced. The device name reads SM-G750A which hints that the device is for AT&T most probably.
Also by reading the information from the UAP of the device, the specifications of the device have been recreated. According to it, the device would be having a 720p display though the size of the display hasn’t been revealed yet. Also the device would be having a quad core 2.3 GHz processor, which only suggests us that it would be having the Snapdragon 800 chipset.
Also the device would be running on the Android 4.3 Jelly Bean, but the version could change till the time of release. So this could be the US version of the Galaxy S5 Neo, or also it could be the Galaxy S5 Mini. We would get to know about it only at the time of official announcement which is not far.