Yes you can.
I work for a telecom provider in Canada and do the support for these devices. Blackberry devices do not need any type of data plan in order to work. Most modern phones are designed to have two capabilities: data and voice - so they are always split into two separate functions. For Blackberry devices you can launch the "Manage Connections" icon, select "Mobile Network Options" and turn the data feature on or off. The "mobile network" check box is what turns the phone's radio on/off. The radio is used to establish communication with your wireless carrier.
As far as what plans your carrier has, I have no idea but the phones themselves don't need a data plan to work.
One other thing... very often with voice plans you will get a slow pay-per use data access for older web pages (called WAP pages). There is a pay-per use charge (usually per kilobyte) however most carriers let you browse their home portal page for free since it links to pay products. You can turn the data feature of the phone off in the options i mentioned above to disable this. Turning this feature off still keeps your wifi working by the way.
One last point... Blackberry.com lets you download apps to your computer and install them over a USB cable to your device. So you can do full upgrades and app installations from Blackberry App World Online. So you don't need a data plan if you want to add apps to the phone.