Common symbols found on phones include bars that show signal strength, letter and number identifiers that display network type, and Bluetooth logos that mean the device is ready to sync with external components. Symbols vary by operating system and phone type, and not all phones use the same set.
Phones running the Windows Phone operating system use a crossed-out symbol to represent a lack of a signal and a crossed-out SIM card icon means the system cannot read or find an inserted SIM card. G, E, 3G, 4G and H indicators tell users what type of network the phone currently uses, and a single triangle means the phone is roaming beyond its home network. A radio transmission symbol indicates Wi-Fi is active, and the letters fn mean the function keys are locked or currently active.
Smartphone users with iOS operating systems may see many similar symbols, including those for signal strength and network types. The letters VPN inside a box means the system currently connects to or through a closed virtual private network, and a telephone symbol with dots under it indicates the teletype service is active.
Android phone owners may see a satellite symbol indicating the phone's GPS is active, and the Wi-Fi symbol is similar to that of Windows phones, but it points straight up instead of at an angle. Android phones also display an airplane for airplane mode and the letter R next to the signal strength bars indicates roaming.