Based on the following Cisco Webex help page "Silent Monitoring" feature isn't supported on BroadWorks Contact Center and Cisco Webex for BroadWorks Calling service.
https://help.webex.com/en-us/article/xga73p/Webex-App-%7C-Supported-calling-options
We need to have silent monitoring feature to be supported on the above mentioned services same as is currently supported as on UC-One (Communicator) product in order to allow us to migrate customers who currently use UC-One to Cisco Webex for BW Calling.
Currently if a supervisor use FAC #82 + ext number of an agent they can barge into the agent active call to monitor it if the assumption is the agent uses Cisco Webex for BW desktop client app.
The feature works where the supervisor initiating the silent monitor is not heard on the agent's call. They are passively listening to the call (as expected). One of the main issue is we see a change on the agent's Webex UI that provides an indication that silent monitoring has been initiated - the Webex UI screen rearranges and presents itself in the conference call format (with a side panel where the participants are listed). The supervisor is not included in the participant list visible to the agent in the Webex side panel.
The second main issue is that the agent losses its ability to transfer the call in case he/she needs to. The call truns to be a conference call when the supervisor initiates the silent monitor which this is not the case on UC-One application.
As business case information, Masergy has total of 466 Call Center customers with the total number of agent seats of 10,885.
