I tried 3CX system for a week. The system seems good, but there are two things make me in trouble. First, it assumes authentication ID equals to phone number. Second, it seems it cannot handle multiple NICs/IPs on one machine. it seems randomly bind to an IP address so sometimes system work well; sometimes I get one way voice; and sometimes I get no voice at all. SIP part always work. Any idea about the second problem? I know I have to wait for next version to solve the first problem.