You can set your mobile phone to find a network automatically or you can choose a network manually. If you select a network manually, the network connection will be lost if you're out of range of the selected network.
Step 1 of 5
Find "Carrier"
Tap Settings.
Step 2 of 5
Find "Carrier"
Tap Carrier.
Step 3 of 5
Select network
Tap the indicator next to "Automatic" to turn automatic network selection on or off.
Step 4 of 5
Select network
If you turn off the function, tap the required network (eg. Singtel Mobile).
Step 5 of 5
Return to the home screen
Slide your finger upwards starting from the bottom of the screen to return to the home screen.