The Borough (or Simultaneous) Call signal was transmitted by telegraph exactly the same in all Boroughs. A key to remembering it was "FIRE, FIRE, HELP, HELP, HELP"
For example one Borough Call signal transmitted for Manhattan's Morgan Post Office fire at 9th Ave & W 30th St of 12/15/1967 was 66-676-99-22-7729 which indicated that the fire was at Manhattan (66) Box (676) and the additional help would be from Queens (99) a Second Alarm Assignment (22) from Queens Box (7729) which would provide the assistance (Engine Companies Only were to respond on these signals).
Basically the Term Simultaneous Call and Borough Call were the same, the difference being a Simultaneous Call directed the greater alarm assignment for one Box Location to respond to another. If it involved another Borough, the term Borough Call applied. A Simultaneous Call could be used within a Borough, for example, to direct a downtown Brooklyn assignment to a major fire in Coney Island.
These telegraph signals were a way to get a lot of apparatus on the road quickly, probably faster than it can be done today with either VOICE ALARM OF COMPUTER.