CIDCW
Caller Identification on Call Waiting or Calling Line Identifier on Call Waiting (Type 2)
A telephony network service that transmits the caller's telephone number and, in some systems, the caller's name to the called party's telephone equipment during the ringing signal or when the call is being set up but before the call is answered - Also refered to as Calling Line ID, CLI, CLID and CLIP. The Call Waiting feature is an added function which provides Calling Line ID information when off hook.
CML's CIDCW products decode the 'stuttered' dial-tone which indicates a call waiting.