Dodge, If you want data plan without voice, therefore you can't use data plan.. Like me, Few weeks ago, when My fiancee switched her bberry for my sk3. I came over tmobile store, i required them my phone tranfered sk3 to bberry. I asked them don't want the voice but just data plan. They tried to explained it to me in more details, if i wanted data without the voice, that meaning can't using internet web and email. Unless I have voice (cell phone number) on data plan, not just BBerry. all sidekick, cellphone, smartphone and mda demand with the voice.. that is their policy.. simple, don't give your cellphone numbers to friends or randoms..
If you don't believe, then go to talk to retailer, he/she will tell you the exact what i tell in this post... its up to you..