Step 1. Exit 3CX Phone.
Step 2. Go to C:\ProgramData\3CXPhone for Windows
Step 3. Download and extract https://cdn2.hubspot.net/hubfs/2070090/Busy%20Light%20PhoneApp%20Folder%20V14.zip
Step 4: Replace Current PhoneApp folder located at C:\ProgramData\3CXPhone for Windows with PhoneApp Folder from Zip File
Step 5: Plug in Busy Light 
Step 6: Start 3CX Phone for Windows
Step 7: If busy light is Green then proceed to make test call and see if light changes. If not reboot and then see after 3CX Phone for Windows app start if light is green then try test call.