This tutorial shows how to pair to a mobile network.
INSTRUCTIONS & INFO
From the clock screen, swipe up from the bottom edge of the screen.
Scroll to, then tap Settings.
Scroll to, then tap Connections.
Tap Mobile networks.
Tap Use mobile networks.
Auto on/off will only turn on mobile network connection when Bluetooth connection is lost.
Always on will maintain a connection to the AT&T mobile network at all times, in the event that its Bluetooth connection to your phone is lost.
Always off uses the least amount of battery power. Gear S will only send and receive notifications and calls from the Gear S phone number, and will have no access to Samsung Gear Manager functions.