I own a BB pearl, I know it's not the same but this may help.
What I did, was reconfigure the wi-fi. AKA re-set it up for wi-fi. I notice if it doesn't get full signals, or the signals are sketchy, you will not get service. I have since downgraded to Pay as You Go...and no longer can use the awesome BB features or online features.
Wherever you got the BB from, check their website, and register your phone if you can. You may need an update downloaded to your phone.