A method, implemented by a system coupled with a wireless telecommunication network, of estimating a number of persons gathering at an Area of Interest for attending a public happening during a time interval on a day, wherein said Area of Interest is defined by an Area of Interest center and an Area of Interest radius and is covered by a mobile telecommunication network having a plurality of communication stations each of which adapted to manage communications of user equipment in one or more served areas in which the mobile telecommunication network is subdivided, the method comprising the steps of: a) defining ( 504, 506, 524 - 528) a plurality of calculated radius values of the Area of interest radius, and, for each calculated radius value: b) identifying a number of relevant served areas ( 405a-d) among the served areas comprised in the Area of Interest; c) identifying ( 510, 512) a first number of user equipment associated with at least one event record of a corresponding event of interaction occurred between the user equipment and the mobile communication network during the time interval on the day of the public happening within the Area of Interest; d) identifying ( 514, 516) a second number of user equipment associated with at least one event record of a corresponding event of interaction occurred between the user equipment and the mobile communication network during the time interval for each one of a predetermined number of previous days preceding the day of the public happening within the Area of Interest; e) combining ( 518, 520) the first number of user equipment and the second numbers of user equipment for obtaining a statistical quantity; f) computing a normalized statistical quantity by normalizing the statistical quantity with respect to the radii of the relevant served areas ( 405a-d); g) computing an optimum radius value of the Area of Interest radius as the average of the calculated radius values weighted by the normalized statistical quantity; h) counting the number of persons, owners of user equipment, gathering for attending at the public happening within the area of interest having the Area of Interest radius equal to the optimum radius value. a) defining ( 504, 506, 524 - 528) a plurality of calculated radius values of the Area of interest radius, and, b) identifying a number of relevant served areas ( 405a-d) among the served areas comprised in the Area of Interest; c) identifying ( 510, 512) a first number of user equipment associated with at least one event record of a corresponding event of interaction occurred between the user equipment and the mobile communication network during the time interval on the day of the public happening within the Area of Interest; d) identifying ( 514, 516) a second number of user equipment associated with at least one event record of a corresponding event of interaction occurred between the user equipment and the mobile communication network during the time interval for each one of a predetermined number of previous days preceding the day of the public happening within the Area of Interest; e) combining ( 518, 520) the first number of user equipment and the second numbers of user equipment for obtaining a statistical quantity; f) computing a normalized statistical quantity by normalizing the statistical quantity with respect to the radii of the relevant served areas ( 405a-d); g) computing an optimum radius value of the Area of Interest radius as the average of the calculated radius values weighted by the normalized statistical quantity; h) counting the number of persons, owners of user equipment, gathering for attending at the public happening within the area of interest having the Area of Interest radius equal to the optimum radius value.