1. To block a number, from the Start screen, tap the Messaging tile.
   
2. Tap the menu icon.
   
3. Tap Blocked messages. 
   
4. Within blocked messages, tap the menu icon.
   
5. Tap block list.
   
6. To add a numer to the BLOCK LIST tap the Plus icon.
   
7. Add the desired number, then tap Block.
   
8. Tap and hold on desired blocked number to  open Unblock menu.
   
9. Tap Unblock number.