"If you have an incoming call while you are on the line, the Call Waiting feature will alert you. You may then put the first call on hold, while you answer your second call. It will greatly reduce missed calls due to a busy phone.
When a second call is received, you will hear a beep on the line.
To speak to the second caller, simply press the flash button for approximately on second. The second call will then come on the line.
When you have finished speaking to the second caller, simply press the flash button and you will be reconnected to the first caller.
You can alternate between calls by pressing the flash button each time."