Detainees are allowed visitors and to receive and make phone calls on an unrestricted basis but there can be limitations based on practical reasons regarding the safe running of the detention centre. Drunken visitors will not be admitted, nor will visits in large numbers at the same time. Visiting hours should be generous and flexible and at times that are suitable to the visitor. More flexibility is shown to members of the family than to adult friends of the detainees. These visitors can never be searched bodily, however, if it is necessary, a visit can be supervised for reasons of security. But a visit by legal counsel can only be supervised at the request of the detainee or legal counsel. If it is suspected that illegal objects have been handed over to the detainee then the detainee may be bodily searched after the visit. Visits should in general take place privately in a suitable room. If a visit is denied for some reason, the detainee has the right to appeal the decision. If a visitor does not wish to give his or her name then this is not in itself grounds to deny a visit, nor is it in itself sufficient grounds to decide to supervise the visit.
NGOs and UNHCR have unlimited access to detention centres. However as of 2018 NGOs have to designate in advance the persons from their organisation who visit the detention centres. As far as the author is aware, this has not caused any particular issue in practice.
 Ch. 11, Section 4 Aliens Act.