telephone_extension
1. [ noun ] (telecommunications) an additional telephone set that is connected to the same telephone line
Synonyms: extension_phone extension
Related terms: telephone
2. [ noun ] (telecommunications) an additional telephone operating on the same line
Synonyms: extension_phone
Related terms: telephone
Similar spelling:   telephone_exchange
  telephone_company
  telephone_system
  telephone_number
  telephone_service
  telephone_message
  telephone_circuit
  telephone_operator
  telephone_conversation
  telephone_interview
  telephone_directory