The icons in the status bar at the top of the screen give information about iPhone:
Shows whether you’re in range of the cellular network and can make and receive calls. The more bars, the stronger the signal. If there’s no signal, the bars are replaced with “No service.”
Shows that airplane mode is on—you cannot use the phone, access the Internet, or use Bluetooth® devices. Non-wireless features are available. See Airplane Mode.
Shows that your carrier’s 3G network is available, and iPhone can connect to the Internet over 3G. Available on iPhone 3G or later. See How iPhone Connects to the Internet.
Shows that your carrier’s EDGE network is available, and iPhone can connect to the Internet over EDGE. See How iPhone Connects to the Internet.
Shows that your carrier’s GPRS network is available, and iPhone can connect to the Internet over GPRS. See How iPhone Connects to the Internet.
Shows that iPhone is connected to the Internet over a Wi-Fi network. The more bars, the stronger the connection. See Joining a Wi-Fi Network.
Shows over-the-air syncing or other network activity. Some third-party applications may also use this icon to indicate an active process.
Shows that Call Forwarding is set up on iPhone. See Call Forwarding.
Shows that you’re connected to a network using VPN. See Network.
Shows that iPhone is locked. See Sleep/Wake Button.
Shows that iPhone is set to work with a TTY machine. See Using iPhone with a Teletype (TTY) Machine.
Shows that a song, audiobook, or podcast is playing. See Playing Songs.
Shows that an alarm is set. See Alarms.
Blue or white icon: Bluetooth is on and a device, such as a headset or car kit, is connected. Gray icon: Bluetooth is on, but no device is connected. No icon: Bluetooth is turned off. See Pairing a Device with iPhone.
Shows battery level or charging status. See Charging the Battery.