While on a call, tap the Add call icon.
Enter the 10-digit phone number and tap the green Call icon.
To dial a number from the contacts list, tap the Contacts tab.
Tap the desired contact.
Tap the desired Call number.
After the second call is connected, tap MERGE CALLS.
The conference call is now initiated.
Tap the End Call icon to end the conference call.
The call is now ended.