The system will record the prospects line so it records the conversation the rep has with the prospect when the rep calls the transfer agent the system puts the contact on hold and continues to record the contact/prospects line. It doesn't record the private warm conversation the rep has with the transfer Agent.
When all lines are merged it is recording the rep, transfer agent and the contact/prospect. When the rep leaves the bridged call the system continues to record the transfer agent and the contact/prospect. It will continue to record the contact/prospect until the contact/prospect hangs up their phone (disconnecting the contact/prospect from the PhoneBurner phone system)