Why am i getting the message that my Samsung Galaxy S4 sim card not detected?

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AC Question

Samsung Galaxy s4 sim card not detectied

I am going on to my 3rd replacement phone now. My phone reboots after saying it can not detect my sim card. This last phone I have is doing it again. Only difference now, is that is does not detect my sim card, but when I put in my wife's, it detects it. I can also put mine in my wife's phone and it works fine. Why would it not detect mine but my wife's sim?