It's December and Christmas is just around the corner. But business never sleeps. And nor does your company's telephone system. For it always has to be "on duty". Whereas most employees take time off over the holiday season, it's business as usual in some places.
It depends on the industry. Say, industry A closes for the holiday season, industry B reduces operations but still has to be reachable by phone and industry C has to stay open for business. But let's have a closer look at the individual situations using examples.