Something in my dim distant memory tells me it could be an old AT&T type data frame.
Spot on. "110" connectors which use a different punchdown tool to Krone terminations.
I used a set of that stuff some years ago for a job. I was wiring up multiple sets of serial ports - Chase IO Pro units. For my needs, I didn't want to use their standard pinout on the RJ45s, plus it's a right pain trying to swap out a unit when you patch them direct. So I made a large board, pigtails with RJ45 plugs on one end to go into the IO Pro units, and through these terminations to get to the pinouts I wanted on standard patch panels. TBH a lot of work for not a huge benefit but it did look impressive !
Underneath those punchdown blocks will be a plastic frame. The fixed wiring is laid into that, with the wires in the slots. The connector blocks are them pushed in, thus IDC terminating the back end of the block to the wires in the slots behind. You can now connect to the front side either with patch cords, or by punching down.
As the patch cords are "non standard", these would be most useful as an intermediate distribution point - as in bulk cabling comes into the back, then individual cables come off the front to the workplace sockets. This is a technique sometimes used in an environment where stuff moves around from time to time - eg cubicle farms. Allows the endpoint sockets to be re-done without having to re-cable all the way back to the distribution room.
Anyway, those connector blocks come in multiple sizes - 2, 3, 4, 5? pair - to suit the application. But, they clip on and can't be easily removed once pushed into place.
Some more reading :
http://en.wikipedia.org/wiki/110_block
And a Molex datasheet
http://www.rockby.com.au/DSheets/30440.pdf
