The widespread use of mobile devices using third-generation (3G) and Long-Term Evolution (LTE) networks has led to the development of various applications that take advantage of the always-on Internet connectivity provided by these networks. Instant messenger (IM) or social network services (SNSs) like Facebook and The Impact of Application Signaling Traffic on Public Land Mobile Networks Twitter are some examples of this class of new mobile applications. Traditional Internet applications, such as web surfing and file transfer, are characterized by a usage pattern that has distinct active and inactive phases. An active phase is a period in which several bursts of packets are transmitted, while an inactive phase is characterized by no data transmission during a sustained time period. The traffic pattern of recent and emerging applications that rely on always-on connectivity is quite different. Since the emerging mobile applications support real-time communications services, they are often constantly running in background mode to receive status updates or messages from other parties. The Impact of Application Signaling Traffic on Public Land Mobile Networks Thus, the applications continuously generate short signaling messages such as keep-alive and ping requests to maintain the always-on connectivity. Although the traffic volume of keep-alive messages is not large, frequent short messages can incur a large amount of related signaling traffic in the mobile network. In 3G or LTE networks, the user equipment (UE) and radio access networks keep the radio resource control (RRC) states. The Impact of Application Signaling Traffic on Public Land Mobile Networks The UE stays in RRC Connected mode when it transmits or receives data during active periods and stays in RRC Idle mode during inactive periods. To send even a small data packet, the UE changes the RRC state to the RRC Connected mode prior to transmission. This RRC radio state change generates a lot of signaling messages, resulting in a rapid increase in traffic loading. The Impact of Application Signaling Traffic on Public Land Mobile Networks The amount of signaling traffic leads to two major problems: rapid drainage of the mobile device’s battery and a signaling traffic surge in the mobile network. In , the authors focused on the issues of the energy impact on the mobile device. In this article, we focus on the signaling impact of these applications on public land mobile networks (PLMNs). The signaling traffic surge, or so-called signaling storm, due to the rapid growth in use of The Impact of Application Signaling Traffic on Public Land Mobile Networks these applications is having a serious impact on mobile network performance. The frequent RRC state change leads to increased signaling overhead over the air interface and through the core elements of a mobile network. The effect of signaling traffic loading gets more severe for the core network as the number of UE devices connected to the core network elements increases.Several mobile network operators (MNOs) have experienced severe service outage or degraded network performance due to the increase of application signaling traffic . Furthermore, the stability of the network can also be impacted by signaling traffic when there is an application server failure or outage.