Your employeer needs to wake up. If you need a phone for work, you need a phone for work. Many plans now offer a zillion more minutes then you will need for the office, unless they are pooling their minutes for all of their people, you are just throwing those away at the end of each month.

No matter who you choose, you can always use a calling card if necessary for Canada if the rates aren't great, Onesuite.com for example, who I use for all my long distance calls at home, offers 2.5 cents per minute to canada. Use the minutes on the cell to get access to a local number in the states, then call Canada for pennies.