Login to the Lync URL
https://Lync.abc.com/Cscp/
Single sign on will work for this
Click on Enable Users for Lync Server.
Click Add to add the user for enabling it.
Type the user logon name in search field and click find, select the required user and click ok.
Select pool server from the drop down from Pool list.
Select Enterprise Voice from the Telephony drop down list.
Click on the Enable to enable the user for lync.