1. From the Start screen, tap the Phone tile.
   Note: The call blocking feature may not affect phone calls made or received via third-party apps installed on your device. Please contact third party app developers for assistance with such applications.
   
2. Tap the Menu icon, then tap Blocked calls.
   
3. To block a number, tap the Menu icon.
   
4. Tap Block list.
   
5. Tap the Plus icon.
   
6. Enter the desired number then tap Block.
   
7. To unblock, touch and hold the Desired number and tap Unblock number.