Sometimes you're in a mood when you really don't want to be bothered by pesky unknown callers (or for some, even known ones) and tapping the reject call button once the phone starts ringing just isn't enough.

XDA member ftgg99 has come up with a solution in the form of his Root Call Blocker app for Android. The developer claims his app to be the only one with which you can block calls before the phone actually begins to ring, at a system level. Features include the ability to select a network reply when blocking the call, block numbers whose network IDs aren't available, manage your own accept and reject lists and enable notifications for when a call is rejected.

If you're tired of unwanted calls and would like to give Root Call Blocker a try, visit the application thread to find the download link and more information. As you may have guessed from its name, the app requires root for it to work properly.