I have DW-Contacts and it's very well done.
But in the firewall service I have some troubleshotings.
I made the following settings:
- a Grouplist called "BLACKLIST" with alla the numbers a want to reject
- a new filter containing the "BLACKLIST" group
When a new incoming call is a member of the "BLACKLIST" group
the following message is shown: "Blocking call failure"

isn't blocked. I think it's a bug.

I have a LG Optimus One P500 with:
- AGA ROM 2.2
- software version LG-P500-V20g
- Android version 2.3.3
- kernel version 2.6.35.10-perf
- superuser installed
thanks and good bye