I found instructions on this on page 4-50 of the PDF manual I was given for network emanager. It shows how to create a User Agent to allow someone to go direct to an extension's VM without first ringing the phone. But, the menu options they list don't exist in my network emanager.

It says to go to Advanced Configuration > Voice Mail > Direct Send Voice. I don't have Advanced and as far as I can tell Voice Mail doesn't exist either. The closest I've seen is under System, but it's Voice Mail Data.

How can I set up a button that will go direct to VM without first ringing the phone?