| 摘要 |
PURPOSE:To prevent the titled device from catching a line which is held by others by impressing a common pattern which expressed a key telephone set provided with an operated circuit selecting button and a holding button together with a pattern during holding the line while the line is used for the operated key telephone set. CONSTITUTION:Telephone sets 2a and 2b are connected to a main device 1. When either of line selecting switches 10a and 10b of either of telephone sets 2a and 2b turns on, it is impressed on a discriminating means 4 inside the device 1 through a signal processing means 8. The means 4 discriminates either of telephone sets and outputs to a controlling part 3 and a selecting means 5. The controlling part 3 catches the corresponding circuits (a) and (b). A means 5 outputs a pattern A which indicates the line in use stored in a memory unit 6, and a pattern C to a signal processing means 7 of the telephone set which turns on for the key telephone set in use, and only pattern A turns on for other telephone sets. The same operation is executed for a holding switch 11 and a pattern B which indicates the line in holding, and the line which is held by others can be prevented from catching. |
