This is typically caused by the Telephony Service of Windows not being enabled. This service will need to be enabled in order to access Vendor Options. To do this:
-Click Start-->Control Panel (Or Start-->Settings-->Control Panel)
-Double click Administrative Tools (You may need to Switch to Classic View to see this)
-Double click Services (Alternatively you can click Start-->Run and type Services.msc)
-Scroll down the list until you find the Telephony Service and double click on it
-Set the "Startup Type" to Automatic and click the "Start" button inside this window.
Try accessing the Vendor Options again.