current whereabouts unknown.

"Zig-Zag": Four acoustic radiators joined together in a "zig zag" pattern on both left right sides of a thin short steel pole, completed in 2009 it is currently on the rooftop of Clementi Fire Station.

Sirens attached on appropriate rooftops of buildings can have a custom-made mini server box (which is white) beside the siren, and to the lower section of on-ground sirens, to eliminate remote control of them from the nearby fire stations turning them into sourcing sirens.

Signals
There are a total of four signals sounded by the sirens, they are:

Alarm signal: Wailing blasts that warn people of a danger or threat and it means for them to move a SCDF air raid shelter.
Used only once on the island's Total Defence Day in 2006. (Sounds similar toSee also

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Automatic Electric Telephones

Automatic Electric was founded in 1891 as Strowger Automatic Telephone Exchange Company by Kansas City resident Almon Strowger, who invented the first automatic (dial) telephone switch in 1889, and a businessman named Joseph Harris. For decades, AE was a leading supplier of telephone equipment to independent (non-Bell) telephone companies across the United States.

Strowger’s first automatic phones were installed in La Porte, Indiana, in 1892. Instead of a dial, these phones featured four buttons, which had to be pushed in sequence to “dial” the number. For example, to dial 374, the caller would push the first button three times, the second button seven times, and the third button four times. The fourth button would then be pushed once to “place” the call. Buttons were abandoned in