Two separate issues: Windows 7 / Outlook 2010 1. Already had the Outlook integration working on one PC. However since updating 3CX to the latest version (could be coincidence) when I right-click a contact, the option to "Call contact with 3CX" is greyed out and cannot be clicked. Windows 10 / Outlook 2013 2. On another PC that was already set up with the same extension/account as of that above, I notice that the 3CX Outlook plugin had not automatically been installed on this machine, nor had I been prompted by it when opening Outlook. When I go to Advanced Settings > Integration from the 3CX client I get a csc.exe application error - unable to start correctly. Followed by another error "Error loading script from folder 'DotNetScripts\Outlook': Could not find file C:\Users\XXXX\AppData\Local\Temp\qx2hzozh.dll". Edit: After installing the latest Win10 updates the second problem has resolved itself.