The public administrations have to check that the third lenders of services and of systems of communication fulfill their responsibilities, it is already as persons in charge of the treatment or, if it is proper, as responsibles for the treatment of the data of the users (in the case of the SMI), since the treatment is subjected to the demands of the principles and guarantees of the European regulations of the protection of data (LOPD, RLOPD, and RGPD). When they consider the choice of a determinate system of instant messaging (SMI) they should take the purpose of the communication, the personal information which it is necessary to treat, into account, especially; the consent of the affected ones; the model of security and the evaluation of impact and the concrete applied safety measures; the mechanisms of certification; the international transfers from data and the location of the servers; the law of information and the transparency, in attention to the forecasts of the European regulations of protection of data.