Sina charges by SMS.

If you move, call 10086 and ask the customer service to turn off Monternet (also called SP master switch). After the setting is successful, any paid SMS will not charge you, and the normal Internet access and SMS sending and receiving will not be affected. This service requires the password of the mobile phone user.

If the customer service makes excuses (such as not having this thing, etc. ) It's not for you, you must be firm, and you must receive the successfully set SMS to ensure that it has been successfully handled. Otherwise, you need to call customer service again.

This so-called SP master switch is specially set up to charge you extra money.

Unicom's mobile phone also has this back door switch. I forgot my name. You told the customer service that it was the "main switch for charging SMS", and she should know.