I think they must have accidentally called (or not known they were still on my voicemail) and it was a training call for new phone reps I assume.  You could hear the trainer telling them to "talk slow but smooth" "it is all about smooth... you can't give a break or they will interupt"  "don't give them a chance to speak until you get down to the questions"

It was actually entertaining.  It was almost four minutes with some dead air before the trainer said "hmm, what's this" (presumably seeing a lighted line) and then an immediate disconnect.  

Not necessarily a bad company, but very funny call...