Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
I don't see a "block call" option when I press and hold number in history. The choices are "details", "delete" and "add to speed dial". I'm using a Lumia 521 and WP 8.1.
For enabling block number you have to go to Settings > Call +SMS filter
Here you can turn ON or OFF call blocking as well as manage blocked numbers and use some advanced settings.
Hope this helps..
Required, but never shown