I would like to set up a simple VOIP system at work, the goal would be to connect a couple of branch offiices to the main office with a VOIP “hotline”. I would like to use something like the X100P and regular phones for this project. All offices are currently running linux servers and desktop machines with full time internet connections (DSL or frational T1 all on NAT behind a linux firewall) . Is there a simple way to do this without the need for a full Asterisk system?
p.s. Ideal operation would be pick up the phone, dial ext. 1,2,3,or 4 and the correct phone at the other office would ring, or there would be a busy signal