5 Channels Available,5 Users could communicate at the same time,but doesn't Impact by each other at the same time. Technical Specifications: Metal keypad for extended life Circuit boards encapsulated in epoxy resin to be impervious to water and condensation A magnetic reed hook-switch to reduce the number of moving parts subject to wear Electret noise-reducing microphone Surge arrestor A service temperature range from -40C to +60C (-40F to + 140F) Waterproof connections with rust roof, stainless steel fittings and faceplate Mounting plate Armored handset assembly