Legal analysis: the prison admission notice is sent to the families of criminals. 1. At present, the practice of mailing admission notices is different in different places. Some are sent to close relatives under the same household registration, and some are filled out according to the address and contact person of the admission file form filled out by the prisoners. 2. There are two ways to query the prison area. One is to inquire about the prison administration in the place where the sentence is served, and the other is to apply to the effective judgment court without knowing which city to serve the sentence. However, some local courts will investigate and some will not. 3. Visitors can generally bring their ID cards and household registration certificates. Before that, you'd better call. Some prisons have regulations on visiting hours, such as which days of the week are closed for visiting prisons. Generally, you can visit the prison at most once a month.

Legal basis: People's Republic of China (PRC) Prison Law.

Article 18 When a prisoner is put into prison, his person and the articles he carries should be strictly examined. Non-necessities of life shall be kept by the prison or returned to the family members with the consent of the criminals, and contraband shall be confiscated.

Article 20 After a prisoner is put into prison, the prison shall notify the prisoner's family. The notice shall be issued within five days from the date of admission to prison.