#conference_call  a telephone call in which more than two people participate
  supertype:  #telephone_call__telephonecall__call__phone_call__phonecall  a telephone connection; "she reported several anonymous calls"; "he placed a phone call to London"; "he heard the phone ringing but didn't want to take the call"
  subtype:  #three-way_calling__threewaycalling  a way of adding a third party to your conversation without the assistance of a telephone operator

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