Why can't I get the Apple SMS verification code?

# Apple SMS verification code can't be received. There may be a problem with the network, and you need to restore the network settings. Why can't Apple SMS verification code be received? We need to operate (3 steps). The model of this demonstration is iPhone13; . System: IOs15.1; +0; The following are the detailed steps:

1 Click General.

In the phone settings, turn on the general options;

1. Click Universal 2, and then click Restore iPhone.

After entering, turn on the transmission or restore the iPhone；;

2. Click Restore iPhone3, and then click Restore.

After entering, click Restore.

3. Click Restore