In one example, a gateway device includes one or more processors configured to determine that a subscriber device has started a first application, determine that the subscriber device has ended a second application, and send a message, in accordance with Diameter protocol, to a policy server device indicating both that the subscriber device has started the first application and that the subscriber device has ended the second application. In another example, a gateway device includes one or more processors configured to send at most one message, in accordance with Diameter protocol, to a policy server device indicating that a subscriber device has started an application, and at most one message, in accordance with the Diameter protocol, indicating that the subscriber device has stopped the application.