ChrisWebbTech I know, and I implemented this even, but, as mentioned in my post, this API is not supported for applications; see the permissions section on the page you reference. You can only get presence when you login in as a certain user, but, most contact solutions do not work that way. By not having this, it means you need to create a "dummy user" that has permissions to see presence of everybody and then use this account to authorize your back-end application (which is also not really the correct way to handle it, since one would normally use the confidential application (client credentials) and accompanying auth flows for this). Contact solutions in general monitor user presence (and by extension, but I guess this is far future, the whole user device) from a back-end application in order to make the right choice in automatic contact routing or dialing for example. To be more precise, I am referring to this user voice item: https://microsoftgraph.uservoice.com/forums/920506-microsoft-graph-feature-requests/suggestions/39219637-application-permission-for-presence which most of us in the contact center business would really like to see (next to the monitoring of users/calls/devices)