I recently moved from OCS 2007 to Lync 2010. We decided to remove the OCS 2007 deployment and start over fresh with Lync as OCS was deployed before our time and did not seem like a clean deployment. When uninstalling we ran into some errors when un-prepping the forest and domain using LCSCmd.exe. We did get OCS uninstalled so we decided to move forward.
I was able to get Lync 2010 deployed just fine. However when I went to add users that existed on the OCS 2007 deployment to the new Lync 2010 pool and Lync would not let me add them
Lync gave an error message of “Filter failed to return unique result, “[SipAddress: sip: firstname.lastname@example.org]” due to their Active Directory accounts having the old SIP address and pool information on them.
What I did to fix this is removed the old pool and SIP address from the accounts of the users in Active Directory. Here are the steps: