Underground intercom system

At Buenos Aires station, we can hear several interesting things when we stop to listen carefully. For example, the old entrance doors, which rotate, or the magnetic exit doors, which make loud noises. A father and son arrive with one bicycle, and since bicycles cannot pass through these old doors, they need to open a special door on the edge. Until a few years ago, when there was still a ticket office that became an information booth and finally nothing at all, they would open the door for you personally. Now you must contact a central office via an intercom, from which, monitored by a camera, they do it remotely.