I bought an iPhone 3GS that was reset to factory default and doesn't have a sim card (since of course, the seller kept it because it was theirs). When I turn on the iPhone 3GS, it comes up that no sim card is inserted.

So I insert my koodo sim card, and it says it's an unsupported carrier?
I thought all carriers were supported on all phones?

What carriers are supported on an iPhone 3GS?

Also what would buying a new sim card cost?

Random question as well, can a non jailbroken iPhone 3GS be activated without a sim card, or is it possible to jailbreak before activating or what?