source: Danville Gazette (Danville, Indiana) - issue of Thursday, December 9, 1954 - page 1, column 1; Thursday, February 10, 1955 - page 1, column 3:
When Danville got direct-dial telephone service in November 1954, it resulted in a change in how the members of Danville's volunteer fire department responded to a fire. Previously, the public would notify the telephone operator that there was a fire, and then the fire siren on top of the telephone building would be sounded, alerting the firefighters wherever they were to respond.
In February 1955, the Danville Town Council authorized the purchase of 15 crystal-controlled radio receivers (at a total cost of $2,746), which would then be placed in the homes or businesses of the firefighters. The radios would be activated by the operator at the police station, who would then announce the location of the fire over the radio, and would also simultaneously press the button to activate the town's fire alarm. Danville was reportedly the only volunteer fire department in the state that would have a radio alerting system, although other large cities in Indiana (as well as the entire state of Delaware) were already using this system.
The radios replaced a system that (according to a November 11, 1954 article) had been used directly after the switch to the direct-dial phone system. Under that plan, the public was to call SH 5-4567. This would then cause the phones in 10 of the firefighters' homes to ring simultaneously. This system was known as a conference circuit, and cost $900 a year. However, the town council quickly found it to be "costly, inadequate and unsatisfactory."