Using this MPKG application you are able to define blacklists and whitelists for specific numbers.
Install the application on your phone or flash card. When you start it the list will be activated and when you start for the second time it will be disabled.
To create the black/whitelist, please create the following text file in your flash card:
#firewalltype can be black,white or none
As you can see you can use wildcards, which makes the tool very powerful. Please make sure that you remove the comment sign before the number (the "#").
Thanks to Xronos for the share of the application!