I also put this into practice this morning, calling at 01:00 to upgrade a Sunday flight. I was told, however, that a B-26 wasn't a full enough fare, had to be Y. Called back this morning and got upgraded with no problem.

So now I wonder whether B fares qualify for the two-day rule, or did I get an agent that enjoys messing with half-asleep pax trying to get a jump on the deadline? Or did the new oboe on-hold music put me back to sleep and I just dreamed it happened??