Centum Call Seconds (CCS):

In all modern communication systems, voice is first digitized and compressed before any transmission. This allows the system to allocate a fraction of the time for this transmision, in a channel which would otherwise be completely occupied by this voice transmission. Furthermore, particularly in VoIP, the channel capacity can occasionally be much larger than what is required for voice transmission, and compressed voice occupies the channel for a very short time compared to classical transmission. A new (and smaller) unit for traffic is introduced which suits this situation better:

Centum Call Seconds or CCS.

1 Erlang is 1 call occupying the channel for one hour.

1 CCS is 1 call occupying the channel for 100 seconds in one hour.

1 Erlang = 36 CCS