I have a 3cx server running and can call between iOS devices that are connected internally. So I know we are "working". I tested a Mac Softphone and audio travels both ways as well. However, I can not get audio in the 3cx Phone for Windows. Even dialing 9999 for voicemail, it rings and connects, but no audio. (Windows 7) Firewall if off on Client and Server. All of this is internal comm only - nothing thru the corporate firewall (yet).