How to use Call Waiting
You can have only one active call at any given time, which means that if you receive and accept a new incoming call, the existing call will be put on hold. During a call, the Call Waiting feature (if enabled) will use a beep to announce the second incoming call. Call Waiting can be enabled from the Call settings menu.
To accept an incoming call while already on an existing call, press the Accept button on your device. The existing call will be put on hold and you will start the new call.
To switch back to the original call, press Swap or tap on the desired call which will automatically put the other call on hold.
To switch to the new call, press Swap.