The two ports on the bottom are used for a wall charger/car adapter and a variety of extensions including a USB cable. The port on the top is meant for a headset but most users of the phone do not employ a headset because the SPH-N270 is designed with aesthetics in mind.
The lower ports of the device support various peripherals like chargers and USB cables, whereas the upper port is designated for a headset. Notably, the SPH-N270's design focus leads many users to forego headset usage.