[b0x3s]

I downloaded the facebook and twitter app but it says unavailable.

I can go on twitter and facebook on browser but not the actual apps. Do I need a data plan for that?

[Xopher]

You need the service books for that. The service books give your BlackBerry permission to use RIM's push services and applications.

Unfortunately, that probably means you will need to register with RIM (BIS or BES) to grant access, and that requires a data plan. All native apps will probably need a data plan so that it can be registered (Facebook, Twitter, AIM, Google Talk...).

But, you should be able to use 3rd party apps like SocialScope or UberTwitter without a data plan (wifi).

[titusilvering]

Yes, you need BB data plan for all RIM apps to run on your bb.