Hi, now i've installed the latest software (Client 5.1.4492.0 & Server 4510) and i have still only one problem, described here: We have a lot of computers, all connected to the 3cx server. OS on these computers: WinXP or Vista. This problem appears only at those computers, whos OS is Vista. When i (Ext 50, winXP) call my friend (Ext60, Vista), i can't hear him, but he can hear me. When i check the system settings for sound (Micro) at Vista pc (EXT60), it is activated and the volume is 100%. I can also see on EXT60 sound settings (during the call) the signal, when i talk to the micro. So the micro is activated and works. Also my Sound-Settings are OK. Then i call him again (50 calls 60) and i can hear him, everything works fine. Then i call him again, and i can't hear him. Then i call him again 10 minutes later and i can hear him. : : so i can hear him only at every 2nd call. i think that there is something wrong?!? it cannot be by coincidence, or? This problem appears only at incoming calls @ all of our computers with OS Vista. ...call terminated 11:28:19.250 CallCtrl:nLegConnected [CM503007]: Call(47): Device joined: sip:email@example.com:5070;rinstance=fc3b352aa473d744 11:28:19.234 CallCtrl:nLegConnected [CM503007]: Call(47): Device joined: sip:firstname.lastname@example.org:5070;rinstance=bd252b13785b2741 11:28:16.031 CallCtrl:nSelectRouteReq [CM503004]: Call(47): Calling: Ext:60@[Dev:sip:email@example.com:5070;rinstance=fc3b352aa473d744] 11:28:16.000 CallCtrl:nIncomingCall [CM503001]: Call(47): Incoming call from Ext.50 to [sip:firstname.lastname@example.org:5060] We all use the same hardware = Logitech USB Headset perhaps u can help me?