I am using the free Windows 3CX PBX, trying it out at home. I have successfully registered a Cisco SPA504G phone (wired to LAN) and my T-Mobile Google G2 (HTC) phone running the 3CX mobile app (connected to the LAN via WiFi). When I dial the extension for the Cisco (wired) phone from my smartphone, the Cisco phone rings, but when I answer it, I cannot hear any voice from the smartphone in the earpiece of the Cisco, even though I can hear voice in the earpiece of the smartphone from the Cisco. The really weird thing is, if I dial the extension for my smartphone from the Cisco phone I get an immediate fast-busy and no connection. This is all happening on the same LAN ands in the same room. :cry: Any ideas?