I lived in Boulder when they first got that phone number. 499 was a new exchange and National Bureau of Standards moved their phones to a PBX with that prefix, circa '64. So I learned that number then ==> 50+ years… Before that, they had an old style phone patch switch board, and you’d call and ask the operator for WWV, and she’d patch you through if it wasn’t busy.
They had an atomic clock, at one point, THE atomic clock, in the basement of the NBS main building. I would walk home from school every day through the “Bureau” property. If it was really cold out, I’d go through the building for a few hundred feet to warm up. The clock was in a glassed in room, so you could see it, but not get in the room. It wasn’t much to look at, a rack or two of nondescript electronic equipment, with some sort of time display. The fathers of my two best friends worked at the Bureau, so I was exposed to some of the goings on there. Most of what was done there in those years was scientific work in a variety of disciplines.