How to find a list of users associated with a UM Dial Plan?

I am attempting to find users associated with a certain UM Dial Plan. I attempted using the Get-CSOnlineUser cmdlet according to some help I found online, but it showed that no users were associated with that Dial Plan. When I went to delete the DialPlan, it told me I can’t because there are users associated with it.

Hope you’ve already resolved your issue, but if you have not, you may want to post this question on a Skype\Lync\Unified Messaging forum where the community is more dedicated to issue specific to the product you are troubleshooting. Also consider providing information such as the version of the products you are troubleshooting.