Here is a photo taken 1,000m above the ruins of the lost alien city in a Roger Corman film, or 30cm away from a group of doorbells in Taipei. The central block connects visitors to whoever is in the room currently, and the surrounding parts…should be reserved for private conversation. Who knows.
The central block has two columns, left and right. If your friend lives in the "left" apartment, press the left bell button. Here is the question. Where is the room number? That does not exist. It is either left, or right.
I have never managed to remember the difference, even after visiting the same room for several times. But there is a proven methodology to manage this confusion. Press the right first, because it is the right one. Only when it fails, press the left, because it is the one that is left out. I might have received a hostile response for several times, even a hostile look upstairs, but it works.
P.S. One of the smaller blocks on the left shows "212." So that is how these doorbells evolve. The still-hanging umbilical cord shows it is fresh out of the womb. Soon it will mature like his surrounding brothers.