It's easy to use and not consume memory and battery. The call blocker service can be active 24/7 or can be activated by Time Settings.
You can easily add your contacts to blacklist and/or include unknown numbers.
Only for full version ( http://goo.gl/EkGOKL ):
- Auto-activation at phone boot
- Automatic block of incoming calls setting up your favorite days, hours in time setting
1) Block incoming calls
2) Select all contacts, anonymous numbers, or single contact
3) Check your block call history details