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but the error is just as likely to be when they try to read "five, one, point, five, two, zero, nine, zero, one, space, minus, zero, one, nine, five, three, four, eight" off their phone to type in to the dispatch system (especially if they need OSGB coordinates).
Exactly, which is why using what3words through the whole of the incident response is proving effective. what3words has been built directly into many despatch systems. No need for OSGB, just read, type or send 3 words.
Check our page to see if your local services use what3words: 
