Get-CsAdPrincipal is a tragically underused cmdlet. Absent a fully generic Get-CsEndpointObject, it’s the next best thing to Get-ADObject, and is killer when you have no idea what you’re looking for – a User, a Common Area Phone, Conference Dialin Number, Response Group or some crazy custom endpoint used in a Skype-enabled application, especially if all you care about is seeing if a number is available.
There are several scripts for testing each of the Skype for Business object types one by one, and I give some of my favorites at the end of the post; the Get-CsAdPrincipal approach is faster in automation if you’re mostly interested in whether a number is consumed at all, and aren’t concerned with *what* exactly is consuming it.
Get-CsAdPrincipal -LDAPFilter '|(msrtcsip-line=tel:+499112224000*)(msrtcsip-privateline=tel:+499112224000*)'
The LDAP query is checking both the MsRTCSIP-Line and MsRTCSIP-PrivateLine attributes, and there is an asterisk at the end in case the extension was specified separately: tel:+499112224000 and tel:+499112224000;ext=4000 are functionally the same number, but do not look the same to Skype for Business! This is common in places where each line can be directly dialed from outside – that is, much of Europe. I used the attribute names in all lowercase because the mixed-case versions did not work.
If all you wanted was a quick way to check if a number is free or not, you can quit reading now and get back to writing your provisioning script 🙂 If you want to know a bit more about Skype for Business objects, as well as see some really nice stuff for viewing your number pool, stay with me…