Abstract: A system for alert, in a telecommunications network, by a calling user a receiving user belonging to a community of users defined by an alert identifier, and the system including: a telecommunication terminal which belongs to the calling user and includes elements which can be activated by means of a predetermined button, for generation of a communication request including the alert identifier; an obtainability server which is connected to the telecommunication network in order to receive this communication request, and comprising: elements for receiving by the network the location coordinates of the terminals which are connected to the said network; and elements for selecting of a user belonging to the said community of users, such that the location of this user is the closest one to the terminal of the calling user; and elements for call redirecting in order to place the calling user in communication with the selected user.