How do you use Berlin crosswalk signal boxes?

I see these all around town and nobody seems to know how to use them – even my German colleagues. We’re engineers, so we feel pretty stupid and inadequate around them…

The majority of people I’ve seen either ignore them or look at them confusedly and try to slap the three black dots – like a cat to a printer – to no avail.

Obviously there are a lot of different kinds, ranging from old and busted to some having mini LCD screens – but only a few are actually press-able buttons.

What’s the deal with them? How do you use them?

Berlin Crosswalk Signal Button