This is a really interesting sneak peek at one of the most secure places on the planet, specifically looking at the comms infrastructure.
The phone system currently on board Air Force One will be two years old next month. Made by the defense contractor L-3 Communications, the so-called Airborne Executive Phone (AEP) plugs into L-3 Communication's Global Secure Information Management Systems (GSIMS) which uses its own IP-based architecture to secure connection. This is not the standard airplane phone slash credit card reader you saw on your last flight to Miami.
One of my favourite little details is the red/green light that indicates if the current line is secure or not.
The plane is also wired for secure and insecure video conferencing and has "seamless passenger information interfaces."