China Construction Bank: Why do I need to enter SMS verification code when canceling SMS financial service with mobile banking client?

China Construction Bank official reply:

This is because your branch has turned on the security verification switch to cancel the SMS primary mobile phone number service. After the switch is turned on, you need to enter the SMS verification code when canceling the change of the main mobile phone number account, SMS transfer and SMS payment through the client, and you don't need to check the SMS verification code when canceling the change of the deputy mobile phone number account.