You can intercom another phone in the office by dialing an 8 before dialing their extension number. They will hear a distinct beep and then your voice over the speaker phone. They can answer back hands free. If they are on active call when you try to intercom them, they have the option to answer, reject, or ignore the incoming announcement.
Dial 8+Ext number and press the soft ‘Dial” key found at the bottom of the display screen screen.
Make your announcement using the handset or the speaker key on the phone.
The extension dialed will hear a notification beep and then your voice.
If that extension is on an active call, the phone will treat the intercom as another incoming call which can be answered, rejected, or ignored.