A fire alarm system comprises one or more fire alarm addressable modules (3), which interface with a fire alarm loop (1) along which data and power may be transmitted, and a voice alarm system comprising one or more amplifiers (6) connected to respective speakers (7) for transmitting voice alarm messages. The or each fire alarm module comprises a message store (22), means for interfacing with an amplifier (6) of the voice alarm system, means for interfacing with the fire alarm loop (1) and means for interpreting signals from the loop (1) and for selecting an appropriate message for transmission from the message store (22).