I have an phone 7 and an iPhone 6 Plus that is not updated and I tried putting my SIM card in it but it won’t activate how to I change that

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If you can't activate your iPhone or iPad (Wi-Fi + Cellular) - Apple Support

You state you have two iPhones and you state you tried to put a SIM card in it. Exactly what it are you referring to, the iPhone 7 or the iPhone 6 Plus? What happens when you put the SIM in, are you seeing an error? If so, what is the exact text of the error you see?