At the modernization stage of information and telecommunication systems of the national security subjects of Ukraine there is a problem of information reliability when sharing data is used. For estimation of the probability of the information and its properties violation it is necessary to determine the quantity of information entered the component of the system. Also all the information that is used by companies and country, must be checked for intrusion and properly protected. The paper presents the method for determining the quantity of information that flows into the telecommunications system considering aging factor. This method uses dynamic parameters of information and considers different factors of environment. Also the testing was conducted and results are presented.