Abstract: A telephone network which can be placed in a dangerous or explosive atmosphere is disclosed. The telephone network includes a manual exchange, one or more telephone sets and one or more limiter-repeater circuits connected with the telephone sets by telephone lines. The one or more telephone sets do not include any supply sources, but each include a solid-state amplifier which requires only a low supply voltage and has low energy dissipation. The solid state amplifier is supplied with operating voltage from supply sources in the exchange through the telephone line.