From LedHed's Wiki
TrixBox
TrixBox CE is an Open Source Linux Distribution centered around Asterisk.
http://www.trixbox.com/products/trixbox-ce?utm_source=trixboxOrg&utm_medium=link&utm_content=products-ce&utm_campaign=fonalitysites
Askozia
Askozia is another Open Source Linux Distribution centered around Asterisk.
http://www.askozia.com/
Astlinux
Astlinux yet another Open Source Linux distribution focused on Asterisk.
http://www.astlinux.org/