Call Waiting lets you put one call on hold while you answer a second one, then alternate between the two.
How To Use:
While on the phone, a gentle tone alerts you to another call. Press and release the receiver button to find out who is calling. By clicking again, you can go back to the first call. To turn off Call Waiting for a particular call, press *70 before you make the call. A busy signal will be given to your callers during the next call you make.