https://www.hylafax.org/archive/2000-12/msg00065.php

Try this:
192.168.*


 var/spool/fax/etc/hosts.hfaxd

In config File

/etc/chan_dahdi.conf

Set to Zero

callgroup=0
pickupgroup=0

http://www.rmalekghasemi.ir/file/SipElastix.txt

http://the-asterisk-book.com/1.6/der-context.html

http://linux-zone.org/forums/thread4037.html

http://www.rmalekghasemi.ir/file/pr-new.rar

http://www.voip-info.org/wiki/view/Asterisk+CLI

http://www.rmalekghasemi.ir/file/IAX2Elastix.pdf

https://wiki.freeswitch.org/wiki/Freeswitch_Gui

http://serverfault.com/questions/502420/what-is-the-allow-anonymous-inbound-sip-calls-option-under-asterisk-sip-setti

And BlockList Block Callerunkown

http://serverfault.com/questions/394399/how-to-stop-registration-attempts-on-asterisk