Well Steven, an outage involving three DS-3s would likely be related to an OC-3 failure (an OC-3 at ~155 megabits/second will carry three DS-3s or just over 2,000 voice channels). I'd guess one of two failure types caused your emotional trauma: Traditional "back hoe fade" or an OC-3 to DS-3 mux went on "time out" for a while.
For example, at my work we've got several kinds of access -- one flavor has a small mux (a Fujitsu FLM-150) arranged on a SONET ring to a companion mux in a nearby CO. That's great, except that both sides of the SONET ride in the same fiber sheath -- so if it gets dug up (the aforementioned syndrome of "back hoe fade") down she goes! Also, of course, if some of the common stuff in either mux (on either end of the SONET circuit) fails down she goes!
And who knows? Maybe this mux in San Bernardino wasn't even configured for SONET -- Maybe it was just single ended!
Like many things in life now-a-days, communications is more fragile than we might expect or like!