transmitting, by an application or an application layer functionality of the user equipment, an application access request message to an application authorization function or functionality of the user equipment or of a core network of the telecommunications network, wherein the application access request message comprises at least one piece of credential information related to the application or the application layer functionality;

determining, by the application authorization function or functionality, that the application access request message is valid, wherein access of the application or the application layer functionality to at least one data transmission session between the user equipment and the core network is to be allowed only in case the application access request message is determined to be valid, and wherein access is to be disallowed in case a respective application access request message is determined to be invalid; and

based on determining that the application access request message is valid, transmitting, by the application authorization function or functionality, an application access grant message to the application or the application layer functionality; and

accessing, by the application or the application layer functionality, the at least one data transmission session between the user equipment and the core network, wherein the core network provides the user equipment with data connectivity to a data network, and wherein the at least one data transmission session is a protocol data unit (PDU) session;

wherein the user equipment comprises a session access control function or functionality which polices access of the application or application layer functionality to the at least one data transmission session according to a decision of the application authorization function or functionality.