The general detention center stipulates when you can visit your friends.

According to Article 52 of the Measures for the Implementation of the Regulations on Detention Facilities (DecreeNo. Ministry of Public Security 126):

Meeting with detainees shall be conducted at the time and place specified by the detention center, and the regulations on meeting with detainees shall be observed.

Generally, the number of meetings with detainees is not more than two, and the number of people meeting each time is not more than three, and the meeting time is not more than 30 minutes. If there are special circumstances that require a meeting on a non-meeting day or increase the number, number and time of meetings, it must be approved by the leaders of the detention center. Lawyers entrusted by detainees are not limited by the number and time, but should be held during normal working hours.

In violation of the regulations on meeting management, the detention center may give a warning or order it to stop the meeting. After the meeting, the detention center shall send the detainees back to the detention room after physical examination. Upon the application of detainees or their relatives and friends, conditional detention centers can arrange remote video interviews for detainees.

Extended data:

According to Chapter VI (DecreeNo. Ministry of Public Security 126), correspondence, meetings and inquiries of the Measures for the Implementation of Detention Center Regulations:

When meeting with detainees, they should hold valid identity documents. When the lawyer entrusted by the detainee meets with the detainee, he shall also hold a lawyer's practice certificate, a certificate of law firm, a power of attorney or a letter of legal aid. The police of the detention center shall examine the relevant certificates and vouchers of the meeting personnel, fill in the registration form of meeting the detainees, and make arrangements in time.

If the detainee needs to make a phone call, he should apply to the police. After approval, I will use the fixed telephone in the detention center to make calls, and the telephone charges will be borne by me in principle. Detainees should abide by the management regulations of the detention center, generally not more than three times, each time not more than 10 minutes.

People's Daily Online-Measures for the Implementation of the Detention Center Regulations (DecreeNo. Ministry of Public Security 126)