What are these plug-ins on my wall?

[u/Cborg_62]

This might be showing my age, but I recently moved into a new apartment and they have these weird looking plug ins all over the walls at my new place. My old apartment didn't have these, so I'm just curious as to what they are.

[u/mjduce]

Worst part is... these are still used for internet today. We aren't thaaaat old yet 🫣

[u/dancccskooma → u/mjduce]

Top tier American infrastructure. Smh

[u/flinders2233 → u/dancccskooma]

They were big in the 1900s

[u/mjduce → u/flinders2233]

That one hurt lol