As a special note up-front, PBXtra prior to version 2010+ does not support Whisper. Whisper is a function that allows an administrator or manager to talk directly to an agent who is actively on a call without the customer hearing.
Fonality systems support Barge/Monitor at the Call Center Edition level and higher.
Both features have been combined into a single interface for the end-user. Barge is a permissible feature, so you can restrict which individuals in your company can use this feature.
You can use HUD to monitor/barge, or dialing *66 (*MO) plus a valid extension number will allow you to monitor the call that extension is making or the next call that extension makes. The users on the call will not be able to hear you. You must have the HUD - Barge permission over the extension you're monitoring.
There are two methods for initiating a Barge from HUD:
Click on the B icon when someone in your company is on an active call. The icon will not appear if the person is not currently on the phone.
A warning appears that you must accept before the Barge function executes.
You can prevent this warning from appearing again by checking the box in the lower right-hand corner.
Once the Barge function executes, you are connected to the call in progress with your voice muted. This is technically considered Monitor mode.
If you would like to join the call with audio, simply click the Mute icon indicated in the graphic to the left.
You can also right-click on the user's contact block to display a menu of options. In the image at right, the Monitor/Barge function is highlighted by the cursor.
Select this option (you must have permission!) and the Barge function executes as with the explanation above.