Occasionally Lync fails to remove a Response Group call from the database once the call is completed.
You can delete the stuck record from the “rgsdyn.MatchRequests” table directly on the SQL server:
1. Right-click the table and edit top 200 rows
2. Find stuck record and then delete
It is best to do this after hours or while there are no other active calls so you will only see a single stuck record.
You also can run the command “DELETE FROM [rgsdyn].[dbo].[MatchRequests];” to delete all records from the table. If there are many records (as all active calls in Lync are listed in this database), you can identify your one by the QueueId; look at “rgsconfig.Queues” table to see which id your queue has.