[The alert algorithm: why, for whom, how, and when?].

Phone cardiopulmonary resuscitation (CPR) assists any cardiac arrest witness, previously trained or not, through standardized instructions given by phone. These instructions are intended to guide the bystander in checking for responsiveness, opening the airway and checking for adequate breathing, and to initiate chest compressions in case of apparent death. The "Algorithme Liégeois d'Encadrement à la Réanimation par Té1éphone" (ALERT) is an original phone CPR protocol helping the dispatchers to guide callers during the dispatcher's time window, between the beginning of the call and the Emergency Medical Services (EMS) arrival on scene. Its use has been demonstrated to increase the frequency and performance of bystanders' initial CPR efforts. Such improvement might increase the survival chances of out-of-hospital cardiac arrest victims (OOHCA).