Broadcast Group buttons enable you to talk to multiple counterparties at once. When you select this button, you will broadcast to all the pre-selected counterparty connections at one time. Each counterparty can respond back to you, but not to other counterparties in the active broadcast.
This is also known as an all call and it is a popular feature used by the broker community. Broadcast Groups are managed through the buttons Advanced Settings menu (Figure 1):
Figure 1 Advanced Settings
Note: Refer to the Knowledge Article found here for further information on configuring a Broadcast Group.