Read help info
In flight mode the connection to the network is deactivated, so as not to cause interference with sensitive equipment in e.g. a plane or a hospital. You can still use the remaining functions when flight mode is activated, but you cannot send messages or make calls. Follow these instructions to activate or deactivate flight mode.
Find "Manage Connections"
Activate or deactivate
When the box next to the menu item is unticked, flight mode is activated.