Telephone subset arrangement

A telephone subset circuit arrangement comprising

• first and second line terminals for respectively connecting the subset to first and second conductors of an exchange line,
• a transmission circuit connected between said first and second line terminals,
• a loop current circuit,
• a battery, and
• a line switch circuit further comprising
• control means associated with the transmission circuit and having power terminal means for applying energizing power to enable said control means and hook-switch signal input means responsive to a control signal for thereupon producing a line switch signal,
• first controllable semiconductor switch means responsive to said line switch signal and having a control element coupled to a first output of said control means and a conductive path forming a switching element in series with said loop current circuit,
• second controllable semiconductor switch means for, when the subset is in an on-hook mode, connecting energy from said battery to said power terminal means,
• third controllable semiconductor switch means for applying said control signal to said hook-switch signal input means, and
• hook-switch means for, when the subset is in the off-hook mode, rendering said second controllable semiconductor switch means non-conducting to thereby disconnect said battery from said power terminal means, and rendering said third controllable semiconductor switch means conducting to thereby couple said power terminal via the transmission circuit to said first and second line terminals.