Cellular Connectivity and the Software-Defined Vehicle
A Core Safety System
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Alex Vakulov
01/23/2026 
Modern cars are no longer just machines that occasionally connect to the internet. They are built to stay connected at all times. Features like driver assistance, remote diagnostics, live navigation, and in-car apps all depend on a steady data link, making connectivity a fundamental part of how today’s vehicles are designed and operated.
At the center of this transformation is the embedded SIM, now evolving into eSIM and iSIM. What was once a simple cellular module for emergency calls has become the secure communications backbone of the software-defined vehicle, enabling AI-powered features, over-the-air updates, data services, and remote control of critical vehicle functions.
As vehicles become rolling data centers, connectivity decisions now directly affect safety, cybersecurity, and compliance.
Connectivity as a Core Safety System
In modern vehicles, more software runs every second than in an entire data center rack from ten years ago. Advanced driver assistance systems, battery management, navigation, infotainment, fleet telematics, and autonomous driving stacks all depend on constant access to cloud-based models, maps, and services.
AI features depend on this connection even more. Vision and perception models are updated as new driving situations are learned, navigation uses live traffic and hazard data, and predictive maintenance relies on telemetry from large vehicle fleets. Autonomous and assisted driving systems also need regular updates to remain accurate and safe.
Cellular connectivity is now treated as a safety-critical system similar to braking or steering. If this link fails, over-the-air updates stop, vital telemetry is lost, and cloud-assisted AI functions begin to degrade. Consequently, a disconnected vehicle is not simply less convenient; it becomes progressively less safe.
Automotive SIMs vs Consumer SIMs
Consumer SIM cards were designed for short data sessions, human use, and devices that are easy to replace. Vehicles operate under very different conditions.
Automotive connectivity relies on embedded SIMs, usually in MFF2, eSIM, or iSIM form, that are soldered directly into the telematics control unit or the vehicle’s system-on-chip.
This design allows the connection to survive years of vibration, temperature extremes, and electromagnetic interference, while also preventing physical tampering or removal. Because vehicles are expected to stay connected for ten to fifteen years, the SIM and its security credentials must remain stable and protected for the entire life of the car.
The network layer is also built differently from consumer mobile services. Automotive SIMs typically operate on dedicated access point networks that isolate vehicle traffic from the public internet. They often use static IP addressing so backend systems can securely reach the vehicle when needed. Data is carried over encrypted tunnels, such as IPSec or TLS, between the vehicle and the manufacturer’s cloud, with critical telemetry and safety-related traffic given priority. Together, these elements create a virtual private network environment optimized for machine-to-machine communication rather than smartphones.
The Vehicle Network Backbone
Connectivity enables vehicles to function as nodes in a distributed computing platform. When a connected car turns on, it establishes a cryptographically authenticated tunnel to the OEM backend. Inside that tunnel flows a continuous stream of data:
- Vehicle state, including speed, braking, steering, battery, and faults
- Sensor summaries used for ADAS and autonomy validation
- Location and map corrections
- Software health and security logs
- User commands from mobile apps
- OTA updates and configuration changes
This network design depends on the SIM behaving more like infrastructure than a consumer subscription. Unlike phones, which can switch users, devices, and carriers freely, a vehicle’s SIM must remain active, secure, and reachable for more than a decade. It must support ownership changes, cross-border operations, software upgrades, and evolving network technologies without ever compromising the vehicle’s ability to authenticate and receive updates. That is why automotive SIMs provide persistent identity, stable addressing, and long-term cryptographic trust, allowing OEMs to reach every vehicle at any time for recalls, security patches, and regulatory updates.
This same network backbone enables over-the-air updates. Before built-in connectivity, software updates required a visit to the dealer. Today, most major manufacturers run OTA pipelines that resemble modern software deployment systems. They use the vehicle’s secure data channel to deliver safety fixes, powertrain and driver-assistance performance improvements, security patches, new features, and updated maps and interfaces.
From an engineering standpoint, this allows problems to be corrected quickly and systems to evolve over time. From a business standpoint, it supports feature activation, subscriptions, and long-term service models.
For fleets and robotaxis, this capability becomes operationally critical. Operators rely on continuous connectivity to track vehicles in real time, adjust routes based on traffic and charging conditions, deploy new AI models across entire fleets, and remotely disable or reconfigure vehicles when abnormal behavior is detected.
The OEM Telecom Partnership
Connectivity is no longer a late-stage add-on. It is designed into the vehicle platform from the start because it affects safety, OTA delivery, cybersecurity, and regulatory compliance. So, OEMs and mobile network operators now operate as long-term technology partners rather than simple service providers.
These partnerships typically include:
- Global roaming and coverage planning
- Private APN and VPN infrastructure for vehicle traffic
- SIM and eSIM lifecycle management for ten to fifteen years
- Continuous security monitoring and incident response
- Joint testing of new radio and connectivity technologies
- Compliance with regional data protection and safety regulations
The shift from a one-time vehicle sale to ongoing service delivery depends on the car remaining continuously connected to the OEM backend, since features, updates, and entitlements are enforced through that connection.
Many OEMs also deploy multi-operator eSIM profiles to enable vehicles to switch networks for reliability and cross-border operation. This ensures that safety services, updates, and telemetry remain available even when a single carrier is unavailable, making telecom infrastructure part of the automotive software supply chain.
OTA and Vehicle Cyber Risk
As connectivity becomes central to vehicle operation, cybersecurity cannot be limited to onboard software and electronic control units alone. The cellular network, SIM identity, carrier infrastructure, and cloud services that keep vehicles online become part of the vehicle’s functional and safety perimeter. Understanding how this connectivity is built, managed, and protected is essential to understanding modern automotive risk. That is why any discussion of the software-defined vehicle must ultimately touch on cybersecurity.
- SIMs are part of the security boundary
The SIM is the vehicle’s network identity. If SIM credentials, eSIM profiles, or carrier control systems are compromised, attackers can impersonate vehicles, block OTA updates, or redirect traffic. This can be used to inject malware or prevent critical security patches from reaching affected cars. Protecting SIM provisioning, profile switching, and carrier APIs is therefore as important as securing vehicle ECUs and backend systems. - The mobile network is part of the attack surface
Vehicles depend on private APNs, routing controls, and VPN tunnels inside carrier networks. A failure or breach at the carrier level can disrupt telemetry, updates, and emergency services, even if the vehicle's software is not compromised. Automotive security must extend into telecom infrastructure, not stop at the TCU. - OTA creates supply chain risk
OTA pipelines connect OEMs, suppliers, cloud platforms, and mobile operators. A compromise at any point in that chain can affect entire fleets. This is why modern OTA systems use signed firmware, staged rollout, rollback capability, and continuous verification before code is allowed to run on a vehicle. - Fleet scale amplifies the impact of every flaw
A vulnerability in a vehicle platform does not affect one car. It affects thousands or millions of vehicles running the same software and connectivity stack. Incident response must be designed for fleet-wide containment and recovery, not single-vehicle repair. - AI depends on data integrity
AI models for perception, navigation, and driving rely on fleet telemetry and feedback loops. Poisoned or manipulated data can degrade behavior even when software remains intact. Secure transport, validation, and monitoring of data streams are required to protect AI functions. - Zero Trust is now required
Automotive networks are moving toward Zero Trust architectures. Vehicles authenticate to backend systems, backend systems authenticate to cars, and every update, command, and data exchange is verified. No component should be trusted by default, including carrier networks and internal services.
Conclusion
As vehicles evolve into software-defined platforms, cellular connectivity becomes inseparable from safety, reliability, and trust. The SIM, the mobile network, and the OTA pipeline are no longer supporting components. They are core parts of the vehicle itself. Securing the modern car, therefore, means securing the entire connectivity ecosystem that keeps it alive, updated, and safe over its lifetime.
Tags: cybersecurity SDVs Automotive
