1) On a computer using a dial-up connection, phantom (meaning ghost) dialing is a term used to describe what occurs when a computer's auto-connect feature has been enabled and the computer attempts to dial out and establish an Internet connection on its own.
2) In mobile wireless communication, phantom dialing is a term used to describe what occurs when a user unintentionally presses a pre-programmed auto-dial number on their cellular telephone keypad and unintentionally initiates a phone call.
In the United States, phantom dialing is a problem for 911 emergency centers, especially since many cell phones are configured to dial 911 (the emergency center) automatically when either a "9" or a "1" is pressed.
When emergency services receives a phone call, the operator must, by law, remain on the phone long enough to determine whether or not the call is an emergency. If the operator listens and determines that the call is probably a result of phantom dialing, they may terminate the call, but must dial back the caller and verbally confirm that there is no emergency.
Operators across the United States report thousands of such calls daily and most phantom dialers say they were unaware they made a call. Users report that they may have dropped the phone, sat on it, put it in their pocket or otherwise jostled it, hitting auto-dial and inadvertently initiating the call. Phantom dialing can be prevented by using the cell phone's keyguard, a feature that locks the keypad, or by disabling the auto-dial feature.