Mínimum criteria in deprivation of liberty 141. The presence of female personnel at EDM should be ensured, when women are deprived of liberty, as stated by the CPT in paragraph 23 of its 10th General Report. 142. During the visits made to these facilities, it has been observed that, at some of them, the use of mobile phones is permitted. The general policy should be to authorise the use of mobile telephones without cameras. The use of these telephones would imply a certain control by the persons responsible for the centre, such as may be the obligation to return them at the established resting times, or other controls necessary to safeguard the safety of one arrested person in particular. 143. It has been observed, and this is a reason for concern, that the technical system used to make telephone calls through a switchboard operator might not preserve the privacy of the calls, should this be the intention of the persons responsible for the switchboard. For this reason, a communication system that duly safeguards the privacy in communications should be put in place. 144. It could occur that various penalties for serious offences to be served at an EDM be joined, so that the stay of the arrested person could exceed two months and one day even should it not exceed four months. This means that an arrested person could remain deprived of liberty for longer than a person who perpetrated a crime, but the latter is entitled to the vis-á-vis meeting on serving a sentence at military prisons which have an area enabled for the purpose. Accordingly, the NPM considers that the Book of Internal Rules (section 5.5) should contemplate such possibility, since this kind of visits is not specifically prohibited by OM 97/1993. 145. It should be pointed out that EDM should have leisure and reading material, in addition to adequate sports facilities and material. 146. Likewise, it would be desirable for all EDM to have partly roofed yards, for the arrested persons to be able to go out of doors in poor weather conditions. Yard at the EDM of Tenerife 67