I was recently setting up Exchange UM with SfB and came across this error when trying to call the subscriber access number. I found this in the event log of the Skype for Business Front End Server.
Dialplan [DialPlan.domain.com] is not recognized by routing application
Cause: Dial plan does not exist, or Skype for Business Server 2015 does not have permission to read the relevant Active Directory objects.
If the dialplan is valid, then run exchucutil.ps1 in appropriate Exchange forest to give permission to Skype for Business Server 2015. If the dialplan is not valid, then clean up proxyAddresses attribute for the affected users.
I had already ran exchucutil.ps1 but i remember i added the dial plan after as i jumped ahead of myself so perhaps its worth running again. i went back to the exchange server and checked in Exchange Management shell and towards the bottom of the output of exchutil.ps1 i still had open i found
Under DialPlans is said not found !
So as suggested in the event log i ran exchutil.ps1 again and this time i see the dial plan added.
i tried again and it worked. Sweet.