Interestingly (at least for a flagship), it appears to be a dual-SIM version, with the mono-SIM version apparently picking up model number GT-i9500 -- a number that would fit in with the series so far.
It slots in where the smartphone connectivity kit rests inside the armrest and, when a suitable LTE SIM is inserted (this prototype model was rocking Verizon) will utilize the car's antenna to get you great signal.
Sitting in the middle of that strip is the 8-megapixel camera, as well as a covered slot for microSD and SIM cards (SIM access is blocked on this WiFi-only model).