Unlocked Iphone 4 unable to connect to Koodo network.

I have an unlocked Iphone 4 and I set it up for a plan with Koodo the other day and I haven't been able to get service ever since. The phones been unlocked on other networks, such as Bell and T-Mobile, and has been used with different simcards, which all work fine. Koodo recognizes the phone/network but won't connect to the network. When I'm in settings and go to "Carrier", Koodo, Bell, and Rogers all show up if not on automatic, but none will connect due to "Restricted Network". I have tried restoring the phone and still nothing. I spent a few hours on support calls with Koodo but continuously was told the same thing while my theory of the simcard being damaged was ignored. I went into Walmart where I received the plan and simcard and they told me to talk to Apple just in case and also go to a Koodo kiosk...Going to call Apple Support, but figured it won't hurt to see if anyone else has run into this same problem! I don't know what to do! Help me please!