Hi: I am new to VOIP and doing some research at the moment. I cam across three open Source products (Asterisk, OpenSer and 3CX). My understanding is Asterisk is PBX server and OpenSer is SIP server. My questions are does 3CX compare to Asterisk or OpenSer? If 3CX similar to OpenSer, can it be integrated with Asterisk. How good 3CX compared to linux bases systems? Is it scalable? Your help is very much appreciated.