First thing is we need to check to see if that BlackBerry is compatible with koodo. Not all of them are especially if they were originally bell or virgin models. Check using the online tool here: http://bit.ly/1cczSKQ
If it turns out to be compatible, the next thing to check is the network mode. It can't be set to 2g only. So check that by navigating to go to menu---options---mobile network---scroll down...network mode: select whatever mode will give you 3g.
If that works, we need to register your service books so navigate to options--advanced system setting --- host routing table --- press the menu (BlackBerry logo) key --- scroll to register now and select it --- tap ok --- hit the end key
You should get a message that you're registered
Next we need to be sure you're on a BlackBerry specific plan, I'll assume you are since you're coming from a torch.