#telephone_system__telephonesystem__phone_system__phonesystem  a communication system that transmits sound between distant points
  supertype:  communication_system__communicationsystem  a system for communicating
  subtype:  MEDLINE  the computer-based telephone system of the U.S. National Library of Medicine that provides rapid linkage to MEDLARS
  part:  transmission_line__cable__line  a conductor for transmitting electrical or optical signals or electric power
  part:  central__telephone_exchange__telephoneexchange__exchange  a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication
  part:  switchboard__patchboard__plugboard  telephone central where circuits are completed with patchcords
  part:  telephone_set__telephoneset__telephone  electronic equipment that converts sound into electrical signals that can be transmitted over distances and then converts received signals back into sounds; "I talked to him on the telephone"
     part:  mouthpiece  an acoustic device; the part of a telephone into which a person speaks
     part:  telephone_receiver__telephonereceiver__receiver  earphone that converts electrical signals into sounds

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