To unlock a mobile device when a passcode has been properly implemented requires entering the correct PIN, password, pattern, or other passcode. In theory, a passcode such as a PIN could be guessed given enough time and perseverance. To prevent someone from trying to guess a passcode over and over, mobile devices can be set to perform defined actions after a certain number of incorrect attempts have been made.

For iOS devices, the device is disabled after five failed attempts, as shown in Figure 1. On the sixth failed attempt, the device remains disabled for 1 minute. Each failed attempt after six results in additional waiting time. The chart in Figure 2 shows the results of failing to enter the correct passcode.

For extra security, turn on the Erase all data on this device after 10 failed passcode attempts option, shown in Figure 3. If the passcode fails 11 times, the screen goes black, and all data on the device is deleted. To restore the iOS device and data, you must connect it to the computer to which it was last synchronized and use the Restore option in iTunes.

With Android devices, the number of failed attempts before lockout depends on the device and version of the Android OS. It is common that an Android device will lock when a passcode has failed from 4 to 12 times. After a device is locked, you can unlock it by entering the Gmail account information used to set up the device.