The FCC is proposing (PDF) a public "robocall mitigation scorecard" that would grade phone companies on how well they block illegal spam calls while avoiding false positives on the legitimate ones. "The Scorecard will empower consumers and encourage providers to continue to combat illegal robocalls by providing the public with an assessment of the effectiveness of voice service providers' efforts to protect consumers from illegal robocalls," the FCC Consumer and Governmental Affairs Bureau said in a public notice. Ars Technica reports: The scorecards could include call-blocking statistics along with data on customer complaints and enforcement actions. The FCC said scorecards could grade providers on a number scale, with letter grades, or by classifying providers as low risk, medium risk, or high risk. The proposed tool would rate wireless, wireline, and VoIP providers on efforts to block robocalls and their "actual results in protecting [consumers] from illegal robocalls," the FCC said. "In practice, that means moving beyond a simple administrative checklist (i.e., did the provider file the right paperwork, did they offer the right tools) and toward a composite set of metrics that reflects both operational practices and measurable outcomes, including how often legitimate calls are blocked."
Whether the tool is useful for consumers will depend on how it's designed, how easy each provider's scorecard is to find, and what data sources it relies on. The proposed scorecard would apply to domestic voice service providers with retail customers, but not telcos that operate solely as wholesale or intermediate providers. "Combatting the scourge of illegal robocalls remains the FCC's top consumer protection priority... As proposed in today's public notice, the FCC aims to develop a scorecard that will give consumers more information about the measures providers are taking to fight illegal robocalls, and it will also incentivize providers to improve their efforts," FCC Chairman Brendan Carr said in a press release.
Cellular or mobile networks have become a favorite target for Chinese APT and other hackers trying to:
Collect location data
Eavesdrop on voice conversations
Intercept confidential data.
To understand what these hackers are doing and how to protect your organization against it, let’s delve into how mobile networks work.
What is a Mobile Network?
A cellular network is not a single antenna or a single piece of infrastructure, but a layered system that lets moving devices stay connected wirelessly while the network manages identity, coverage, mobility, and routing in the background. At the edge is the UE, the user equipment: essentially the phone together with its SIM. The SIM proves who the subscriber is, while the phone provides the radio interface and the user-facing functions. From the user’s perspective it feels simple: the phone has signal and connects. Technically, that simplicity is created by several coordinated layers working at the same time.
The Radio Access Network (RAN)
The access layer is the RAN, the Radio Access Network. This is where base stations communicate with phones over the air. Different generations use different names for roughly the same role: BTS in 2G, NodeB in 3G, eNodeB in 4G, and gNodeB in 5G. Behind that sits the core, which acts like the brain of the network. It authenticates the user, keeps track of where the device is, sets up calls and data sessions, and connects traffic toward other networks and the internet. Coverage is then divided into many cells, and frequencies are reused carefully across cells that are far enough apart to avoid interference. That reuse is one of the key reasons cellular systems can serve millions of users with limited spectrum.
The Handover
Mobility is handled through handover. As a device moves, the network silently transfers the connection from one cell to another so that a call, stream, or download can continue without the user noticing. The complete path is therefore UE to RAN, RAN to core, and core to the internet or another network. The telemetry reinforces that this is an active, managed system: signal quality, connected cells, traffic load, uplink, downlink, latency, and packet loss all describe the health of the connection. So after defining what must stay inside the lab, this gives us the basic architecture we are allowed to study safely: device, access network, core, cells, and mobility working together as one coordinated network.
The Control Plane vs the User Plane
Building on the architecture of UE, RAN, core, cells, and handover, the next distinction is about what kind of traffic is moving through that architecture. A cellular network carries two very different conversations at the same time. One conversation is about managing the connection itself, and the other is the actual content the user cares about. That difference is captured by the split between the control plane and the user plane.
The control plane is signaling. It is the network’s coordination layer: registering the device, authenticating the subscriber, tracking where the device is, deciding how calls and messages should be routed, and maintaining the session as the user moves. The user plane is the payload: voice, video, web traffic, app data, and messages carried through the channels that signaling has already established. A simple way to think about it is that the control plane is the set of instructions that says where traffic should go, while the user plane is the traffic itself.
This split matters for security because the two planes have different characteristics and different risks. Signaling tends to be small, structured, and network-wide; payload traffic is usually larger and more local to the user’s active session. They also run through different systems and are protected in different ways. The important insight is that attacks do not always need to break encryption on the content itself. If someone can manipulate signaling, they may be able to influence where calls, SMS, or sessions are routed. So the defensive focus is not only protecting the data, but also protecting the instructions that control the data.
Summary
Mobile networks have become ubiquitous and essential to our digital life in our modern times. Billions of people rely upon these networks to communicate and transmit data around the world. Despite security measures implemented in 4G and 5G networks, advanced attackers continue to breach these networks almost at will. If you or your organization use these networks to transmit data, make voice calls or otherwise utilize these networks, you are at risk. By better understanding these networks, you are better prepared to protect you and your organization from eavesdropping, data interception, and rogue location services.
To learn more about these systems and how they can attacked, check out our Building Your Own Mobile 4G/5G Base Station where we demonstrate real attacks on our networks.
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