Some Tips from A Shoretel Pro on Installing From the trenches, what I found is that Shoretel/Mitel TDIMedia.sys is not signed, and windows will refuse to install it. Shoretel has never bothered to sign the driver in all the years that this driver has been present in Shoretel. This only applies to Windows Server 2012, 2016 and 2019. If you use Windows Server 2008 R2, this does not apply. Disable Secure Boot in VMWare See this: https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.security.doc/GUID-898217D4-689D-4EB5-866C-888353FE241C.html Procedure Browse to the virtual machine in the vSphere Client inventory. Right-click the virtual machine and select Edit Settings . Click the VM Options tab, and expand Boot Options . Under Boot Options , ensure that firmware is set to EFI . Select your task. Select the Secure Boot check box to enable secure boot. Deselect the Secure Boot che...