KEY TELEPHONE SET

PROBLEM TO BE SOLVED: To improve the convenience for member using the key telephone set by utilizing a centralized mail box recording speeches of designated extension telephone sets in advance in the lump so as to backup a speech content of each extension telephone set. SOLUTION: A voice recording device 4 of the key telephone set is provided with a personal mail box 4d storing each speech content of each party and a centralized mail box 4e storing speeches of extension telephone sets designated in advance in the lump. In the case of storing a voice during a speech, the voice recording device 4 automatically stores the speech contents of extension telephone sets designated in advance to the centralized mail box 4e in the lump in parallel with the storage of the speech contents to the personal mail box 4d.