Samsung phone forgot the screen lock pattern, how to solve?

1. Enter five times incorrect unlock pattern, the screen will display "Please retry in 30 seconds" message, click "OK".

2. Click the "Backup Pin" in the lower-right corner of the screen.

3. Enter the "PIN code" that you have set up before, and click "OK".

tip: 1. When the pin is unlocked, the pattern lock is automatically canceled and restored to the default slide unlock mode.  

2. If unlock failure or PIN code also forget, please contact Samsung Service Center for Unlocking, service center details

Information
* This question takes I959 as an example, the concrete operation takes your mobile phone actual menu as whichever.