That wire was used for prewiring houses by most Bell companies in the 1960's and 70's. It's not actually cross connect wire; the wire insulation on this cable was a little bit thicker. I was still using it myself until the mid 1980's until I could no longer purchase it.
The idea was that once it was installed within the walls, there wasn't much chance of it getting damaged. They also ran it in a continuous loop and fed both ends. This way, even if the cable got cut, it was still being fed from the other direction. It would have to get cut twice in order to actually interrupt service.
The "hooks" are called drive rings. They were the only acceptable method of securing this prewire cable. They also made it feasible to pull a new piece of cable in should the original one fail.
