The Free On-line Dictionary of Computing (30 December 2018):

centum call second

    (CCS) A unit used (in North America) to quantify the
   total traffic running in a network.  1 CCS is 100
   call-seconds.  That means 1 CCS could be 2 calls of 50 seconds
   duration or 20 calls of 5 seconds duration.

   (2002-03-25)