Acer Liquid Z6 - Manual (Page 28)

28 - Making calls
new contact and enter the information. See Adding a contact on
page 22 . Alternatively you can tap Add to a contact to update an
existing contact’s information.
Conference calls
If you have one call on hold and another on line, you can combine
both calls to create a conference call.
After the first call is established, tap to add a second call. Tap
to start the conference call.