What is the problem that the main cartoon card of Apple mobile phone has no signal?

Hello, dear, there is no service on Apple's mobile phone. First of all, I suggest you enter Mijing 06 on the dialing page to see if there is any serial code on your mobile phone. If there is a string code on the mobile phone, it means that it is a card or card holder problem.

In this case, another card will be affected during the call, so there will be no network.

When using an Apple mobile phone, after installing a dual card, the secondary card will have no signal, which is caused by unstable signal. Here are the solutions. First unlock iPhone 12 and click the icon set in iOS 1 1. Then on the settings page, select the cellular network option to enter.