Could not get the Callvia3cx Extension in Chrome to work for the longest time. Running Win 10, 3CX 15 Pro, and latest Chrome. Clicking the callto links would associate to 3CX correctly but nothing would happen in the 3CX softphone. Checked default programs, tried using all the options in the Chrome plugin, nothing. Started playing around with 3CXClickToCall.exe to see if I could get any tel or callto links working at all, and got some weird errors: PS C:\ProgramData\3CXPhone for Windows\PhoneApp> .\CallTriggerCmd.exe --list System.ServiceModel.EndpointNotFoundException: There was no endpoint listening at net.pipe://localhost/CallTriggerService/74915342-b132-44e1-8828-1dba4cd7297a that could accept the message. This is often caused by an incorrect address or SO AP action. See InnerException, if present, for more details. Did some research and it turns out this is due to a permissions error. Relaunched 3CX softphone as an administrator and everything worked like a charm. Modified 3CXWin8Phone.exe to always start up as admin to make the change persistent. Not going to bother with a support ticket on this one, but if you're having the same problem, there's your fix!