Hoot-n-holler (also known as a squawk box system, holler down/shout down circuit and junkyard circuit) is a type of telecommunications system where there is a permanent open circuit between two or more parties. Anyone can speak at any time over a distance without having to pick up a phone or press a button. It is used in, amongst other places, stockbrokerage and warehouse intercom type applications.
Hoot-n-holler capability provides a critical and tightly targeted channel of communication that can support thousands of users around the globe and is an integral part of voice trading systems.
Modern hoot-n-holler systems are sometimes based on IP Multicast. Using IP means old analogue dedicated circuits can be removed, eliminating their associated cost.