Network Unavailable

• Tapping on an available wireless network displayed on your screen will typically cause you to be connected to that network after a brief delay of a few seconds. If you tap a network, wait several seconds and the "Signal" icon doesn't appear at the top of your screen, one likely reason is that the network has become unavailable. To confirm, press the iPhone's "Home" button, then tap "Settings" and "Wi-Fi." The network has become unavailable if it is no longer listed.
  
  

Incorrect Password

• Some Wi-Fi networks require a password. If the wireless network you are trying to connect with requires a password, the iPhone will display a "lock" icon next to its name. If your login attempts to a password-secured wireless network are unsuccessful, it's likely you have input the wrong password. The iPhone typically pops up an error message reporting this error, but if the alert doesn't appear after the first login attempt, try inputting the password again and wait for the error message.
  
  

Network Not Functioning

• Wireless signals are transmitted by a wireless router, but actual Internet connectivity depends on whether the cable feeding into the back of the router is connected to the Internet. As a result, it's possible to successfully connect to a network but not be able to use the Internet. If this happens, try resetting your wireless router. Alternatively, connect to a different network to avoid dealing with a network that isn't working.
  
  

Display Slowness

• The iPhone may be connected to the Internet but the display may not immediately reflect this. To troubleshoot this potential issue, press the iPhone's "Home" button, then tap "Settings" and "Wi-Fi." Re-tap the name of the network you wish to use. The "Signal" icon will usually appear at the top of the screen at some point during this process, confirming that you are connected and can begin using the Internet.