AT&T clock (synchronization)
Wed Apr 1 08:24:37 UTC 1987
> I am unaware of any master clock in AT&T used for sync. I do know
> that it's quite common for the clock in each central office to run
> at a significantly different rate.
I just got a reply back from a friend who works for AT&T in Denver. He says:
> I'm not too sure about how central offices are set up for clock timing.
> My past work in AT&T was with the long-distance calling switches (toll
> offices). Back when AT&T was a monopoly, all the toll switching centers
> kept their internal clocks in sync via a high-precision clock located
> somewhere in Missouri. Presumably (but I'm not sure), the toll centers
> passed along clock sync information to any connected tandem or local
> central offices. With the breakup, all of this stuff must have been changed
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