Synonyms for Telephone extension:

• n.

  •extension (noun)
  • extension.
  •extension phone (noun)
  • extension phone.
  •Other relevant words: (noun)
  • telephone set,
  • phone,
  • telephone.

• Other synonyms:

  •Other relevant words (noun):
  • receiver,
  • telephonics,
  • mouthpiece,
  • telephone booth,
  • transmitter.