Software

 Introduction to the SIP Protocol 
 http://isoc.nl/activ/2005-ENUMSIP/2-Mierla-SipTutorial.pdf

 Session Initiation Protocol (SIP)
 http://www.cs.columbia.edu/sip/

 NIST Security Considerations for Voice Over IP Systems
 http://csrc.nist.gov/publications/nistpubs/800-58/SP800-58-final.pdf

 SIP and NAT - Good introduction to the problem on page one, but: Milkfish != Mediaproxy
 http://download.dns-hosting.info/MediaProxy/NATtraversal-BestPractices.pdf

 REFER RFC 3515
 http://www.ietf.org/rfc/rfc3515.txt

 Klaus Darilion's bookmarks - Voice over IP and related technologies
 http://www.pernau.at/kd/voip/index.html

 Introduction to Speech Codecs
 http://www-mobile.ecs.soton.ac.uk/speech_codecs/

 Introduction to the SIP Express Router
 http://voip.internet2.edu/meetings/slides/200310/SIP_Express_Router.pdf

 Security Engineering - A Guide to Building Dependable Distributed Systems by Ross Anderson
 http://www.cl.cam.ac.uk/~rja14/book.html

 SER - The SIP Express Router by iptel.org
 http://iptel.org/ser/

 Linksys' GPL Code Center
 Link

 Official DD-WRT Website
 http://www.dd-wrt.com/

 Official OpenWRT Website
 http://openwrt.org/

 Busybox uClinux embedded environment
 http://busybox.net/

 Animated Busybox Tutorial
 http://www.linuxdevices.com/files/article018/

 Enhanced OpenWRT User Interface
 http://x-wrt.org

 Windows-based Firewall Configuration Tool 
 http://www.fwbuilder.org/

Hardware

 An application close to Milkfish hard- and software capabilities
 http://www.hpl.hp.com/techreports/2005/HPL-2005-115.pdf

 Doozy Milkfish hardware manufacturers website
 http://www.mycable.de/