These are all fantastic photos. One thing that stood out to me is how prevalent the AT&T/Western Electric blue is everywhere.

Much of my career has been spent inside telephone company central offices, where I've seen equipment from dozens of different vendors. The 5ess is still the sharpest and cleanest looking hardware I've ever seen. Bright white with that distinctive blue accent trim.¹

It's really a timeless look, and shows just how much effort they put into "irrelevant" details like that. A lot of vendors aim for a unified style, but it's usually boring and hard to distinguish from their peers. But AT&T stuff was distinctive, and I don't think it suffered from the passage of time. In other words, it doesn't look retro-futuristic. It just looks nice.

Look at the the 8th photo². You see the cabinets in the background, the keys on the console, the keys on the terminal, the platen knob, and the drawers on the desk. All matching and designed.

[1] (I give Nortel some "anarchy" credit for their courageous use of brown and green. It's fugly in an endearing sort of way :)

[2] https://2.bp.blogspot.com/-vaO-bHVmCQ4/XciOziQqrqI/AAAAAAAAS...