185,000 hits for 'fire radio service"

https://www.elephind.com/?a=q&results=1&r=21&e=-------en-10--11--txt-txINtxCO-fire+radio+system---------

this database focuses on historical newspapers

seeing articles back to 1920s

1925 denver area 200 forest rangers have radios

1945 cal fire getting statewide radios

etc