<climbs onto the soap box>
I just feel the need to tell you that you are making a mistake in thinking that computer experience will allow you to install and program a phone system.
I am going to guess that, no matter what system you try to install yourself, in about 6 months the lawyers will hate whatever system you install and bad-mouth it to everyone. This will be because you do not have the knowledge or experience to set it up and program it properly.
The equivalent of what you are saying about being a computer student is "I have been installing and programming phones for three years so I should have no problem setting up a Linux network as long as I have a manual."
Every phone system has its own terminology and its own set of quirks. With no knowledge of the language, let alone the hardware, you are getting in way over your head.
I hope that the people that you are doing this for know that they have hired a completely unqualified rank amature to handle the set-up of one of their most important business tools.
<climbs down off of the soap box>
