Samsung GALAXY S4 Quick Reference Manual page 19

To return to your original call:
X Tap
places the new caller on hold and activates the previous
call.
To alternate between calls:
X Tap
IMPORTANT: The currently active call is displayed on top and shows an adjacent call
Making a Three-way Call
Three-way calling is similar to a conference call with a total of
three people (including yourself). Make a call to two numbers and
connect them together on your device using three-way calling.
1. From the Home screen, tap
2. Enter the number you wish to call (using the dialpad) and
tap
3. Once connected to the first caller tap
place the first caller on hold and begin your second call.
4. Enter the second party's phone number and tap
(Send).
5. Once the second party answers, tap
connect all three parties.
18
(Swap) to switch to the original call. This
Swap Swap
(Swap) to alternate between the two calls.
Swap Swap
length indicator.
(Send).
(Phone).
(Add call) to
Add call
(Merge) to
Merge