Repeater of telephone calls for noisy areas, powered by telephone line (does not require auxiliary power) is made of a cast aluminum housing with IP66 protection. At normal operating conditions provides a modulated signal sounding of 110dB (SPL) at 1 meter. In its standard version is painted in orange RAL2003, but can be supplied in any other color. Has a telephone interface suitable for any analog telephone line (PABX, PSTN, ATA / FXS of any manufacturer) and can be easily coupled mechanically and electrically to the optical repeaters of the series 450.