A. The normal Lync control panel can't modify privileged users, such as domain administrators. To Lync-enable the privileged users, open the Lync PowerShell and use the Enable-CsUser cmdlet. In the example below, I enable two administrators using their email addresses as the SIP address, but you could also use FirstLastName, SamAccountName, and UserPrincipalName.

PS C:\> Enable-CsUser -Identity "John Savill" -RegistrarPool savdalync01.savilltech.net -SipAddressType EmailAddress
PS C:\> Enable-CsUser -Identity "Administrator" -RegistrarPool savdalync01.savilltech.net -SipAddressType EmailAddress