I would recommend asterisk (http://www.asterisk.org/ http://www.asterisk.org/). Beware: it may be a bit overkill, and configuration is a bit in depth but it wil

I would recommend asterisk (http://www.asterisk.org/ http://www.asterisk.org/). Beware: it may be a bit overkill, and configuration is a bit in depth but it will have all the features want now, and could ever need (check out AGI scripting in your research). You may also want to look into trixbox, which is an asterisk server with a bunch of addons, including full web based configuration already configured. I do not have much experience with faxing but I'm pretty sure if you want to fax from a real machine over VOIP you may run into problems, but I believe there are options for email to fax. As for real phones ringing you'll need ATAs, which can be picked up pretty cheap, or you can go with SIP phones (a bit more pricey but more functions) so the whole idea may be a bit more than you're looking to get into.