Free phone calls at Dartmouth

From Slashdot:

After upgrading their network infrastructure and doing some testing over the summer, Dartmouth University is making free voice over IP available to incoming freshman . It turns out it was costing them more to bill the students for local and long distance than for the calls themselves.

I wonder how many other similar organisations have looked at the cost of billing vs the cost of phone calls. It’s currently impractical here in Australia, due to Telstra having its head up its ass, but I’m thinking of Telus in Canada, who have recently moved their entire infrastructure to VoIP. What does this mean for the economics of long distance calls? Will flat-rate long distance be the future?