Conducting calls with several participants
Requirements:
There is an active call More.
Another call is being made.
Switching between calls
Select the contact.
The selected call is active. The other call is on hold.
Activating a call on hold
Select the contact of the call on hold.
Ending an active call
Select 
End call.
End call. On some mobile phones, the call on hold is activated as soon as the active call is ended.