How does the school check the mobile phone number of the resigned teacher?

When the teacher just joined the job, he registered personal information with information such as mobile phone number and home address.

However, schools are not allowed to inquire about the information of retired teachers for improper purposes, such as selling personal information to illegal websites, which is illegal and criminal.

In addition, you can also contact your teacher's good friends at work. For example, even if she leaves her job, she should keep in touch with her friends' homes or contact them by email.