First add extension to allow blacklisting from the phone. You may renumber *96 to whatever you want to not conflict with other extensions on your system.

[app-system-blacklist]
; *96 <xxxxxxxxxx> 1 - black list phone number <xxxxxxxxxx> to level <y>
; *96 <xxxxxxxxxx>   - Delete system speed dial <xxxxxxxxxx>

exten => _*96XXXXXXXXXX.,1,Answer
exten => _*96XXXXXXXXXX.,2,DBput(blacklist/${EXTEN:3:10}=${EXTEN:13})
exten => _*96XXXXXXXXXX.,3,Wait(1)
exten => _*96XXXXXXXXXX.,4,AGI(festival-script.pl|phone number)
exten => _*96XXXXXXXXXX.,5,SayDigits(${EXTEN:3:10})
exten => _*96XXXXXXXXXX.,6,AGI(festival-script.pl|has been blacklisted at level)
exten => _*96XXXXXXXXXX.,7,SayDigits(${EXTEN:13})
exten => _*96XXXXXXXXXX.,8,Hangup

exten => _*96XXXXXXXXXX,1,Answer
exten => _*96XXXXXXXXXX,2,DBdel(blacklist/${EXTEN:3:10})
exten => _*96XXXXXXXXXX,3,Wait(1)
exten => _*96XXXXXXXXXX,4,AGI(festival-script.pl|blacklisted phone number)
exten => _*96XXXXXXXXXX,5,SayDigits(digits/${EXTEN:3:10})
exten => _*96XXXXXXXXXX,6,AGI(festival-script.pl|has been cleared)
exten => _*96XXXXXXXXXX,7,Hangup

then add these lines and number accordingly before the answer command to your incoming extension

exten => s,?,Zapateller(answer|nocallerid)
exten => s,?,PrivacyManager
exten => s,?,LookupBlacklist
exten => s,?,LookupCIDName

regular part of the incoming extension and then

exten => s,102,Macro(blacklisted1)
exten => s,103,Macro(blacklisted1)
exten => s,105,Macro(blacklisted1)
exten => s,107,Macro(blacklisted1)

then you need to add the blacklisted1 macro

[macro-blacklisted1]
exten => s,1,Answer
exten => s,2,Wait(1)
;exten => s,3,Zapateller(answer|nocallerid)
exten => s,3,Playback(sit)
exten => s,4,Playback(ss-noservice)
exten => s,5,Hangup

get the sit sound file from http://sourceforge.net/tracker/download.php?group_id=123387&atid=696352&file_id=130850&aid=1182658

and put that in your sound folder

then reload asterisk to get the new configuration now pickup a phone and key in *96 then the 10 digit number of your cell phone then a 1 to black list your cell phone then call your system and see if you get the sit sound and then the ss-noservice sound and then hangup

if it works you are done

then pickup your phone and key in *96 and the 10 digit number you want to remove from the blacklist.