3CX works fine on my Vista/HP Pavilion laptop at the same remote location and network that Windows 7/Acer Aspire 5532 does not. On the Windows 7/Acer Aspire 5532, I can see on my remote Asterisk console that I'm registering correctly, and when I make a call I hear ringing... then when the call is completed, silence. I tried my "Echo Test" number and don't hear the announce message on the Windows 7/Acer Aspire 5532. This same echo test works fine on the Vista/HP Pavilion platform. The two laptops are configured as different extensions. At this same remote location, I have a Sipura SPA3000 configured as yet another extension. The 3CX-Vista/HP Pavilion combo can call the SPA3000 and carry on a full duplex conversation. The Windows 7/Acer Aspire 5532 combination can call the other two, but no sound in either direction. The Acer may not have a microphone, but does have speakers, so I'd expect to at least be able to hear the other side of the conversation. Does anyone know why sound won't play under Windows7?