Tempo, 52059242, Alert 340 Nautilus Test Telephone Set, ETSI 90ms TBR, 4mm Plugs and Small Crocodile ClipsFeatures:xDSL FiltersDigital circuit safetyVoltage alarm and Lock-outLoudspeaker listeningVolume controlMicrophone muteTalk/Monitor status LEDBattery low audible toneTone/ pulse diallingRedial (10x24 digit memories)Super Hi Impedance polaritySuper Hi Impedance monitorHigh monitor levelSelectable ringer tonesHigh impact resistanceHigh chemical resistanceReplaceable premium cordsetEasy shoulder placementUnique glass reinforced nylon quick release belt clipThe Alert 340 Test Telephone (A340) incorporates all the Nautilus design features making it ideal for the harsh environment of the Outside Plant. DSL filters are now fitted as standard to reflect the prevalence of this particular technology within the telecommunications sector. A340 xDSL compatible Test Telephones offer Digital Services Protection enabling safe operation in situations where telephone wiring may be carrying Digital traffic, Voltage feed to remote electronics or Hazardous voltages that result from fault conditions or misuse of the cable. The A340 also features loud-speaking (listen only) capability.Selecting "off hook" mode will stop the alarm signal and loop the line without damage to the test set. If the alarm signal persists, it indicates that the voltage on the line is above 120V. In this case the line is not looped avoiding damage to the test set as well as alerting the user to the presence of hazardous voltages.The A340 models of the Nautilus test telephone range offer the essential features that every telephone technician needs; super high impedance monitoring of the line so as to pose as little risk as possible to parallel data services plus protection and warning of conditions such as high voltage and excess current.