I have a pretty basic plan, "More Everything" with 500 MB of data. If I want to Call Canada from the U.S. Verizon will charge me $1.79 per minute. Or for $10 per month I can get a plan with lots of minutes.
Telna Dial-Around lets me call Canada by calling their U.S. number (free from my phone) and they charge me 5 cents per minute. No monthly fee.
Why does Verizon charge $1.79 per minute when Telna can provide the same service for 5 cents? It's a bit of a nuisance to call the dial-around number, then the Canada number, but I don't call Canada often, so ten bucks a month is not worth it.
Why the enormous discrepancy?
Because they can. Upgrade to the new Verizon Plan with 18 GB or more and calls to Canada are included for free. But that will cost you more than $10/m!
Stick with the dial around.