PURE ASTERISK 
The Open Source PBX Revolution ...
My .conf files;
http://linuxcrazy.com/Asterisk/
LINKS;
Asterisk Answering Machine
http://www.smallnetbuilder.com/content/view/24226/72/
voip-info.org (wiki)
The link is on the left, Asterisk
http://www.voip-info.org/wiki/index.php
Asterisk and AsteriskNow
http://www.asterisk.org/support
Trixbox
http://www.trixbox.org/
Asterisk Forum
http://forums.digium.com/viewforum.php?f=1
About IAX2
http://www.voip-info.org/wiki-IAX
Asterisk: A Bare-Bones VoIP Example
http://www.onlamp.com/pub/a/onlamp/2003/07/03/asterisk.html
CallWithUs
http://www.callwithus.com/
Convert .wav to .gsm
sox greeting.wav -r 8000 -c1 greeting.gsm resample -ql
Podcast #9 is my very confusing ramblings about my adventure configuring Asterisk, enjoy...