52.28.6 Conference Calls
Establish a normal (2-way) voice call - party A dials party B
Party A or B dials the third party, C, to add them to the conference; the Dial activity (in A or B) must have Multi-party calling set to Merge.
OR
The third party, C, dials Party A or B, to join the conference; the Answer activity (in A or B) must have Multi-party calling set to Merge.
The party in red (with two "legs") owns the conference:




Any party can end the conference by using the Hang Up activity, which makes it leave the conference
The other two parties will be returned to a normal (2-way) call which either can then end by using Hang Up
Call On Hold
Call Off Hold
Call Off Hold Requested
Call On Hold Requested
Group Call Entered
Group Call Exited
Group Call Modified
Call Leg Attempt
Call Leg Setup
Call Leg Established
Call Leg End
Call Leg Rejected