1. The Signal strength icon will display the strength of the network signal. When you are within range of a cellular tower the indicator will show more bars. If you are not in range of a cellular tower you will have fewer bars/less signal strength.
   
2. If the Signal Strength icon is replaced by an Airplane icon, Airplane mode is turned on and the device will not receive wireless signals.
   
3. If connected to a Wi-Fi network, the Wi-Fi signal icon will display the strength of the Wi-Fi signal and when data is being sent and received.