Only if your carrier has an IM only plan, like the Student Plan available from Telus.
Otherwise, carriers would require a data plan. If you don't have a data plan, you typically would not even be able to see the BBM icon with most carriers.
Which company is your carrier? Can you see the BBM icon? It would be in the Instant Messaging folder and also in the App Switcher, which is accessed by holding down the MENU button. (aka BB button, to left of trackpad.)
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