[K12OSN] phone system

[Paul Lemke]

Hi all,
	This is not closely related to the list. but I don't know who else
to ask. The school I'm currently helping has about 10 rooms. They want to
put some kind of phone system in place to have a phone in each room. (why
they didn't do this when they built the school boggles my mind) We already
have cat5e ran to each room where the phone would go. 

	The question is. are there any open source implementations of a
commercial phone system? Let's just say the bid we got to do the phone
system was a little high for our low budget. So I'd figure I'd ask some
other school's what they do. I was thinking of a VOIP setup utilizing our
totally underutilized Fedora server. 

	Here are the basic requirements:
1. Use phones (not software phones)
2. Voicemail
3. Some kind of "Public Announcement" system

Thoughts? Or can someone point me in the right direction? 

Thanks!
Paul