I just found this on Verizons website
o Initiate Call Waiting:
When you're on the line and a second call comes in, you'll hear a tone to let you know you have another call. When that happens, you have three choices:
Put the first call on hold by pressing SEND. You'll automatically be connected with the second call. To return to the first call: Press SEND again. To switch between the two calls: Press SEND.
Or, end the first call by asking the first caller to hang up. This automatically connects you to your waiting call.
Really.. I have to ask the other person to hang up? That so F'n Stupid... I know this worked on my S4..