Install and provision webclient for telephone service 3CX Windows Client Installation and Provisioning Log in to the 3CX Webclient. If you’re unsure how to log in to the 3CX Webclient, please click here. Click on „Apps“ in the lower-left corner. Select the Windows desktop application. Click „Install“ to download and then install the 3CX Client. Click „Provision“ to set up the installed 3CX Client for use with your user account.