Features and options:
- Accept all calls - pretty self explainatory.
- Accept call from My Contacts only - accepts calls from contacts only, others are rejected.
- Reject all calls - pretty self explainatory.
- White List - accepts calls only from the white listed nos.
- Black List - accepts all call except from the black listed nos.
- Black List Pattern - any no STARTING from the black list pattern list is rejected. For eg. if you enter "123", so all nos STARTING from "123" will be rejected, this is a very nice option with which you can block nos from any particular network, country, city, area or whatever you can think of.
- Finally there is also an option to reply with an SMS.

Important:
- Please uninstall previous versions before installing ver 1.3.
- Also Delete Callfirewall.xml from the Root folder. Previous versions Callfirewall.xml will not work with ver 1.3.
- The XML file for 1.3 and 1.4 are compatible.

Known issues:
- One Ring Delay in Rejecting Calls.
- Ongoing call -> Blocked Caller Calls -> Existing Call is Hung Up.
- Problems with some Radio ROMS where the caller identdification is delayed by Windows by a couple of seconds.

Important note:
CallFirewall has to be running in the background to work, so if you are using apps like HTC X button, etc be sure that CallFirewall is running.

For Smartphone users, please download this software here (349 KB) or its mirror here.

Update Description:
v1.4:
- Selective Call Barring. Now you can restrict selected outgoing calls.
- Add outgoing calls as Appointments.

v1.3:
- Added SMS Black List. You can add numbers as well as names. eg. you put 'abc' as name, then all smses starting , ending and containing 'abc' as contact name will be blocked. The same works for numbers as well so beware.
- Added Silent Startup - Create a shortcut to Callfirewall.exe with 'startup' as parameter and copy to windows/startup/.
- 'Add as Appointment' Timings can now be adjusted by minutes ( + or - ).
- Appointment is now saved in format: "Call from : Mr.X NUMBER Accepted/Rejected", Category : Call Firewall, Reminder Alarm is not set.

v1.2:
- Added option to reject unknown / private / withheld nos.
- Option to Add Accepted calls as calendar appointment.
- Option to Add Rejected calls as calendar appointment.
- Toggle Option to show 'CallFirewall' in 'running programs' / Task Managers.
- Save User Settings so that it remains intact upon restart.
- Completely revamped UI to accomodate new options.

v1.1:
- Added an option when selected, will ask you whether to send an SMS when a call is rejected.

SOURCE

http://www.logic-unlimited.in/callfirewall.php

Reviews:

***** [Dec 9, 2008] by Paul Storer using htc tytn2 wth windows 6.1
The application works just as described. I had a sony erricson T29s a long long while ago!!! This fone had a similar program built in2reject various calls from certain lists etc. yrs old but ahead of its time. The htc has nothng 2 reject calls so this program is excellent dus exactly wot it says on the tin !!!!!

**** [Dec 9, 2008] by art using HTC
I put a number on my black list and I can't get it off or change it somehow...

**** [Feb 23, 2008] by Viet Nguyen using HTC T Mobile Wing
Overall is good. But I have some comment as below:
1) number entering in the white or black list is not flexible eg: phone number '0909376984'I want to enter in the black, I have to enter (090)376984 in the black list otherwise it does not run well.
2)when installing I already selecte storage card but it always install in my device.

***** [Jan 9, 2008] by Contivity using HTC Excalibur/T-Mobile Dash
Great software and meets what I need. I've been looking for something like this for a while.
For Joey with Motorola Q:
Get the SmartPhone Version at http://www.logic-unlimited.com/callfirewall.php

**** [Nov 16, 2007] by kingdoug1973 using htc 8125
I love this program,rude is what im looking for.... I was getting 30 to 60 hang ups a day. This makes the message clear.. 2 days after install no unwanted calls. Only bad things are: 1. You have to set black list w\ add last caller button on bottom of settings screen and 2. I think it would be great if ringer wasnt prompted (voice mail is triggered on reject after ring) but it works just like it says otherwise.

* [Aug 30, 2007] by Rob using T-Mobile Wing
The real problem is if you have the program running, and you have your white list accept on. Someone on your white list calls and you answer. If someone then calls and isn't on you're white list you get disconnected from you current call! Tried with the Smaertphone version on my Dash and the same thing happens. Ruins the program!

* [Jul 22, 2007] by Ezeshara using Treo 700w
Often strange crashes, making my device unstable. I think some commercial program is more usable and stabler than this one, such as MagiCall etc.

* [Jun 29, 2007] by Joey using Motorola Q
The interface doesn't display properly on my phone. Also, like another poster, choosing Black/White list options from menu crashes the unit with the message, "ERROR An unexpected error has occured in CallFirewall.exe Select Quite and then restart this program, or select Details for more information. Selecting details yields the function/call stack, with a "NotSupportedException" and it occurs in "Microsoft.AGL.Common.MISC.HandleAr() inside System.Windows.Forms.Control._InitInstance().

**** [Jun 22, 2007] by Waltan using HP ipaq rw6828
Yea, agree with joey. All block calls shouldn't come thru and should be blocked immediately as this'll appear rude to the caller.

* [Jun 15, 2007] by Li using T Mobile Dash
Error when trying to open open black/white list options.

*** [Jun 11, 2007] by Joey using Cingular 8525
It could have been a great program were it not for letting the call come through just the same. the call should have been blocked right away so as not to appear rude to the caller and make him think you rejected his call when you saw it was him. you would not want to show away clients if you're a professional.

**** [May 21, 2007] by sfrog using ERA MDA Compact II (Qtek 9200?)
Works fine, except that ring is initialized anyway for a about 0,3 sec. On one hand you are notified some one tried to call you, on the other hand it is useles for blocking all connections during e.g. meeting. Caller gets busy tone (same as you select ignore/busy option on the phone). I was looking for something like that for a long period of time. Finally I am getting rid of buissness calls on weekend!