| 摘要 |
PURPOSE:To give assurance to a speaker, by displaying that a main wire, which does not correspond to a main wire key of a key telephone set, is connected to the telephone set, when it is connected, on a display corresponding to an extension key in order to display the main wire state for the telephone set having no key corresponding to the main wire or display. CONSTITUTION:A main unit 1 is connected with (n) sets of key telephone sets 2(1)-2(n), and (m) lines of main wire 3(1)-3(m) via local line interfaces 4(1)- 4(m). The main unit 1 is also provided with a cross point 5 to connect the interfaces 4(1)-4(m) with telephone sets 2(1)-2(n). The point 5 is connected with extension lines 6 and 7. The telephone sets 2(1)-2(n) are provided with displays 24(1)-24(5) corresponding to main wire keys 23(1)-23(5), and a display 28 corresponding to an extension key 27, hold button 25 and an add-on button 26 for conference. When connecting a main wire, other than main wire 3(1)-3(m) corresponding to keys 23(1)-23(5), to telephone sets 2(1)-2(n), that is displayed on a display 28 to give assurance to a speaker. |
