How does Call Back work?

The "Call Back" feature allows you to receive a call back notification on your phone when a called party becomes available (e.g. when you call an on-campus extension that is busy or does not answer). To receive call back notification, press the "CallBack" softkey when you call an extension that is either busy or continues ringing. Note: You cannot activate call back notification if the called party has forwarded all calls to another extension.