How to set up Apple 13 mobile phone without network?

Sometimes when we are talking to others, if we need to check some information online, we will find that the mobile phone can't connect to the network. How to continuously set up Apple 13 telephone network?

How to set Apple 13 without internet when making a phone call?

Apple 13 needs to turn on the VoLTE function when it is set to call the Internet. This function needs to be activated by calling the operator to which the SIM card belongs or sending a short message. Take Unicom VoLTE as an example,

1. Click the SMS icon on the mobile phone desktop to enter the editing information interface.

2. Send DGVOLTE and reply Y to 100 10 to start the VOLTE function.

This paper takes iphone 13 as an example and applies it to iOS 15 system.