ISP Config

https://www.howtoforge.de/anleitung/der-perfekte-server-debian-squeeze-debian-6-0-mit-bind-dovecot-ispconfig-3/

http://lists.sip-router.org/pipermail/sr-users/2014-March/082225.html

http://www.ictinnovations.com/content/kamailio-elastix-installation-and-integeration