From Bright Pattern Documentation
How to Hold and Retrieve a Call
You can place an active call temporarily on hold in order to do some work related to this call without releasing it.
To place a call on hold, click the Hold button
in the top bar or in the Interaction Details panel.
The Active Interactions list will continue to display the call on hold as an active call. The Held status of this call will be indicated by the Hold icon becoming dark grey and displaying the elapsed time of the hold
. On mouseover, the Hold button will change its appearance to Retrieve
.

To retrieve the call from hold and continue the conversation, click the Retrieve button
in the top bar or in the Interaction Details panel.