Using BroadCloud Barge In
This service allows a user to barge in on an existing call, by dialing the Directed Call Pickup with Barge-in feature access code followed by the extension of the user to barge in on. It also allows the ability to pick up another user in the same group while the call is alerting. This feature functionality can be enabled or disabled through the My Account or My Phone portals.
The attached document provides all the information you need to get the best from this feature.