How to set one card to make a phone call without the other card for Apple dual-card dual-standby mobile phone?

Tools/materials required: iphone xs max mobile phone.

You only need to disable the activation of one of the cards. Taking iphone xs max as an example, the setup steps are as follows:

1. Open the phone and find "Settings":

2. Click to enter the settings and select "Cellular Mobile Network":

3. Click to enter the page, and click the following mobile phone number of the main card:

4. After entering the page, find the option of "Enable this number" and click the switch button on the right to turn off this function:

5. Then a notice will pop up, just click "OK" to go through the level: