For Christmas my son gave me an iphone he got from a friend. He said he thinks it is an iphone 3 or 3s. I know nothing about smartphones and am over 50 lol! My questions are: how do I know what kind of iphone it is and if it is compatible with Koodo? On the back it says 16GB but doesn't say anything like iphone 3. Also, he said his friend was with Fido, but he doesn't know if the phone is locked. How do I know. When I turn it on, it just tells me that it needs a sim card. Any help educating this dummy mummy would be appreciated.