The Hooter is used for multi function but the major is for alert on Security Break.

Hooter can be on in following cases,

Security Break (Continuous for Ten Minutes).

Panic Switch Pressed (Continuous for Ten Minutes).

Panic Code Pressed by extension user (Continuous for Ten Minutes)

Test Code Pressed by extension user (Beeping for 5 seconds)

Office Hours (Beeping for 5 seconds)