The first night in camp, one of the guys was playing a moose calling tape, and while lying in bed, we were all giving our best imitations.
The next day, Mick and I were stopped for lunch, and a bull was calling, down in the trees on the other side of the creek. I glassed for 15 minutes, then gave three cow calls. Within five minutes he was crossing the creek, and within one more he was down. That was my first moose, taken with a .338 Winchester and 250 grain Noslers at 400 paces.
The second one was held for about five minutes while I called intermitently, until I crossed the swamp to the only tree around. Same rifle and 210 grain Noslers, paced off at 250. Calling does work.