Hi Rafi,

Barge and cBarge can only be used with "Shared Lines" on IP Phones. The function of Barge is not a "Silent" operation so unlikely to meet most "big brother" setups. Here is the related info;

Barge Using Built-In Conference-Barge Softkey

You can use the Barge softkey only in the remote-in-use call state. A built-in conference bridge proves advantageous because neither a media interruption nor display changes to the original call occur when the barge is being set up. A spinning circle displays at the right side of the prompt status message window at the target device.

When the barge initiator releases the call, the barge call gets released between the barge initiator and target. The original call between the target device and the other party remains active. A barge disconnect tone (beep beep) plays to all remaining parties.

When the target device releases the call, the media between the barge initiator and the other party gets dropped briefly and then reconnects as a point-to-point call. The display changes at the barge initiator device to reflect the connected party.

When the other party releases the call, both the original call and the barge call get released.

When the barge initiator puts the call on hold, both the target device and the other party remain in the call.

When the target device puts the call on hold or in a conference or transfers it, the barge initiator gets released from the barge call while the original call also gets put on hold, in a conference, or transferred. The barge initiator can barge into a call again after the media gets reestablished at the target.

When the other party puts the call on hold or in a conference or transfers it, both the target device and the barge initiator remain in the call.

When network or Cisco CallManager failure occurs, the barge call gets preserved (like all active calls).

Some Cisco IP Phones (such as Model 7940 and 7960) have the built-in conference bridge capability, which barge uses.

The following settings activate or deactivate the built-in conference bridge:

•Enable or disable the built-in bridge by setting the Cisco CallManager clusterwide service parameter, Built-in Bridge Enable, to On or Off.

•Enable or disable the built-in bridge for each device by using the Built In Bridge drop-down list box in the Phone Configuration window (choose on, off, or default). On or off override the Built-in Bridge Enable service parameter. Choosing default uses the setting of the service parameter.

Note To use barge with a built-in bridge, ensure the preceding items are enabled, Privacy is disabled, and the Barge softkey is assigned to each device. Otherwise, to use shared conference bridge, assign the cBarge softkey to each device.

From this good doc;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/4_1_3/ccmfeat/fsbarge.html#wp1027397

If these phones are part of a Cisco Call Centre application then these can be used;

Configure and Deploy Silent Monitoring and Record in CRS

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00801a62a8.shtml

Silent Monitoring and Recording Using Unified Communications Manager

http://www.cisco.com/univercd/cc/td/doc/systems/unified/uc601/feapps/cmmonrec.htm

Hope this helps!

Rob