You can send a page to all the phones in your building by pressing the Page button on your phone. This will be one of the programmed buttons beside the display on your phone.
Please note that paging works slightly different than the old system: When you press Page, you will hear a tone, and when the tone stops, then you can make your announcement. When you're finished paging, please press the Red Phone key shown below before hanging up the phone. This will prevent others from hearing the sound of your handset going back into the cradle.