AT&T clock (synchronization)

[seismo!nbires!vianet!devine]

Mark writes:
> 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
> dramatically.

Bob Devine