We have an aging digital phone system at my office. We would like to replace it with something modern, such as an IP based phone system. I have read a bit here and there, even browsed through some voip beginners books. We have a few quotes with local vendors for IP phone systems, but if it can be done in house, I think we can save a lot of money and get many more features.
I am noticing that all of the features of these systems require add on licences. I have heard of Asterisk, and see that it's implemented in both Zentyal and Clearos. I am a capable Linux admin, but I know next to nothing about voip.
So, I am looking for sound advice from people who know their stuff and/or have been in the same place and found/installed a FOSS solution that worked. What hardware recommendations are there? What is the best way to handle QOS? Do we need seperate network runs to each phone and computer, or can there be one network run to each station with a l2 switch and have QOS handled at the backbone switch?
My current network:
-We will be getting a new EOC (ethernet over copper) line installed with 5 mpbs up/down within a month.
-We have all unmanaged netgear switches, and will be separately upgrading to a pfsense based firewall to connect WAN to LAN. We will be upgrading to whatever managed switch for the backbone is decided to be adequate.
-There are about 30 user computers total, with 5 servers. Three servers running debian linux and two running Windows server 2003.