Convenience device intended to be connected to a plurality of lines telephone

摘要

The device 1 prevents the user having to set itself - same, manually, a line is free when he wishes to call a corresponding. / p & & p & for this purpose, the device 1 comprises a voltage detector of the line 11, which produces a signal indicating that when, at the moment when the user lifts the handset 2 in the intention of an outgoing call, the line which is connected to the device 1 is occupied by a call set up with another telephone connected to the same line. The control circuit 13 of the device 1 then uses this busy signal for controlling the connection of the device with another line.