I bought an iPhone last year here in Canada and had it replaced in an Apple store because of accelerometer issues. When the technician brought out a new iPhone he asked for my SIM card so I gave him my Fido SIM card to activate my phone. Everything went well then when I got home I tried to put in a Rogers SIM card and it worked but then other SIM cards not from Canada wouldn't. It actually had me thinking for a moment that they gave me an unlocked iPhone! Two months later, I tried to jailbreak my phone but encoutered some issues so I had to restore my phone. After the restoration my phone wouldn't work with the Fido SIM it was activated with. It would only work with Rogers.

My questions are, if my phone was activated using a Fido SIM card then why did it work with Rogers before the restoration? And why did it stop working with Fido after the restoration? Also, my phone is model MB499LL indicating it's an AT&T iPhone then why is it locked to Canadian carriers? Doesn't Apple go by the IMEI to determine which network the phone is locked to? Is this a special case or does this happen to a lot of iPhone users?