If truly unlocked, you'll have voice service, at least. I don't know anything about your service plan.
See blackberryfaq.com regarding data plans. FYI if you don't know, you'll need a [b]blackberry data plan[/url] in order to use blackberry or RIM branded data applications. You may find you have access to generic mobile data. If you don't know what you are doing, talk to your service provider and get educated fast. Don't start using data and get hit with a huge per kB bill.