Passive fire defense design parts are used to resist, retard and isolate flames and also the linked smoke and fumes: they don't in by themselves extinguish flames that's why These are classed as 'passive security'. RemoteLync engineering maintains strong wireless connections as many as 1,000 ft in open up locations https://www.thesafetycentre.co.uk/blog/ems-wireless-firecell-systems-from-the-safety-centre/