Ethernet is usually two pair, but cat5 has four. When I moved into a new apartment building I found all the phones were cat5 wiring so I was able to redo three of the outlets to do phone and an ethernet jack, then put a switch in the coat closet, which is where the wiring guys put the junction box.

I can’t recall if I put them back when I moved out. I must have, but I’ve no recollection of doing so. I think I left the junction box in the closet though.