iPhone 7 replacement to the new one

This is a known issue with some iPhone 7 models. Click this link to see if you qualify for the repair program --> iPhone 7 Repair Program for "No Service" Issues - Apple Support

Click on the Contact Support link in the top right of this page to start the service process. If you are still within your warranty period they can replace it otherwise you will have to pay for a repair.

If it’s out of warranty and it’s a hardware fault then your option with Apple is pretty much only to pay for a service replacement. If there’s a repair program for a specific issue then maybe they’ll offer a free service replacement, but I haven’t heard anything about such a program. Otherwise, Apple generally doesn’t do courtesy replacements for free.

Other than that, some suggestions are to switch on airplane mode and then switch off to see if maybe the SIM system resets.

If all else fails, some third party repair shops might be able to diagnose and fix such an issue, but Apple considers that “unauthorized repair”. If it’s just damaged contacts then it’s a fairly simple repair, but Apple would consider it to require a complete replacement.