M2M

What is M2M?

M2M (Machine-to-Machine) is the automatic exchange of data between devices over a wired or wireless network, without a person initiating or intervening in the communication. A sensor, meter, PLC or RTU sends measured values, statuses and alarms to another system, which acts on them or stores them by itself. M2M is therefore much older than the term IoT: telemetry from pumping stations and power grids over telephone lines and radio existed for decades before anyone spoke of the Internet of Things.

M2M is the foundation of industrial automation, monitoring and telemetry, and the base on which IoT and the IIoT are built.

🧠 How does M2M communication work?

Every M2M solution consists of four building blocks, whether it is a smart meter or a remote pumping station:

Communication works in two ways. With polling, the central system queries each device periodically, as SCADA does over Modbus or DNP3. With event-driven communication, the device takes the initiative itself: it reports on a change (report by exception) or at a fixed interval, which saves battery and bandwidth. The second form dominates for wireless sensors that have to run for years on a single battery, and it supports real-time alarms without constant traffic.

🕰️ How did M2M emerge and become standardised?

M2M grew out of process automation and telecoms. For a long time every vendor built its own closed solution; targeted standardisation only started around 2009.

oneM2M defines a horizontal service layer, so that applications can address devices from different vendors in the same way. LwM2M focuses on management: firmware updates, configuration and diagnostics of devices with little computing power, using CoAP over UDP with DTLS encryption. Version 1.1 (2018) added transport over TCP/TLS and non-IP networks such as NB-IoT and LoRaWAN, and version 1.2 (2020) added MQTT and HTTP.

🔧 Which networks and protocols does M2M use?

The choice depends on distance, data volume, energy consumption and whether the link stays on site or runs off site:

Application protocols run on top of the network. MQTT (an OASIS standard, also ISO/IEC 20922) uses publish-subscribe through a broker and underpins MQTT Sparkplug B and the Unified Namespace. CoAP is the lightweight alternative for constrained devices. Inside factories, OPC UA and Modbus remain common, and utilities such as water and energy also use DNP3.

🔄 What is the difference between M2M and IoT?

M2M and IoT overlap heavily; the difference lies mainly in architecture and purpose, not in scale.

A classic M2M deployment can involve millions of SIM cards, so it is not necessarily small in scale. IoT can be seen as the successor that opens M2M connections up to the cloud, edge computing and analytics, and therefore to Smart Industry.

🏭 Where is M2M used in OT environments?

• Process control - an HMI reads real-time data from PLCs via Modbus or OPC UA; machines report status to MES and Historian systems
• Drinking water and wastewater - pumping stations and wells send levels and faults to the central SCADA system via cellular routers or radio
• Energy - in the Netherlands the grid operator reads smart meters remotely and passes consumption data on to the supplier; substations communicate via IEC 60870-5-104
• Maintenance - a vibration sensor reports anomalies to the maintenance system for predictive maintenance and condition monitoring
• Logistics and vehicles - telematics sends location and engine status to a central platform
• Buildings - lifts, fire alarm systems and building automation report faults to a monitoring centre, which improves both availability and safety

📡 What does the 2G and 3G switch-off mean for M2M in the Netherlands?

Many older M2M devices communicate over 2G (GPRS) or 3G. Dutch operators are switching these networks off step by step: VodafoneZiggo ended 3G in 2020, KPN in 2022, and Odido switched off 2G in 2023. Odido committed to supporting 3G until at least 1 August 2026, is keeping it running somewhat longer and will announce the final date at least six months in advance. According to the Dutch regulator ACM, VodafoneZiggo will not end 2G before the end of 2026, and KPN switches off 2G in December 2027. The ACM names older alarm systems, payment terminals and medical alarm devices as groups that may be affected.

A practical approach for OT managers:

1. Inventory every cellular connection in your asset inventory, including the modem type and supported network generations
2. Ask your provider which SIM cards still connect via 2G or 3G; M2M providers can often report this per SIM
3. Replace in good time with LTE-M, NB-IoT or 4G modules, allowing for lead times and site visits
4. Choose remote management with eSIM (GSMA SGP.32) or LwM2M, so that you can switch provider or network later without visiting every device

🔐 How do you secure M2M connections?

M2M devices often run unattended for years in remote locations. The Mirai botnet showed in 2016 what happens when such devices are reachable with factory-default passwords: hundreds of thousands of cameras and routers were hijacked for DDoS attacks. Basic measures:

• No default passwords - unique credentials per device and services such as Telnet disabled
• Shielded network - a private APN or VPN instead of a public IP address, and network segmentation between M2M routers and the OT network
• Encryption and identity - TLS or DTLS with per-device certificates, backed by certificate management
• Firmware updates - included in patch management, preferably remote and signed
• Oversight - network monitoring for abnormal traffic and data usage per SIM card

IEC 62443-4-2 and IEC 62443-3-3 set concrete requirements for components and systems. Since 1 August 2025, wireless devices placed on the EU market must meet the cybersecurity requirements of the Radio Equipment Directive, demonstrated with EN 18031. The Cyber Resilience Act adds a reporting obligation from 11 September 2026 and full product rules from 11 December 2027. Organisations covered by the Dutch Cybersecurity Act, in force since 15 August 2026, must include the risks of their M2M connections in their duty of care.

❓ Frequently asked questions

What does M2M actually mean?

M2M stands for Machine-to-Machine and means that devices exchange data with each other on their own, without human intervention. A sensor, meter or PLC, for example, sends measurements to a server that responds automatically.

Is M2M the same as IoT?

M2M and IoT are not the same, although they overlap heavily. M2M is the older form in which a device communicates with its own server for a single task, while IoT connects devices through open platforms and the cloud to combine and analyse data.

What is an M2M SIM card?

An M2M SIM card is a SIM for devices rather than phones, with a tariff aimed at small data volumes and often a private APN. M2M SIM cards are usually more robust or embedded as an eSIM and are managed centrally through the provider’s portal.

Which protocols are used for M2M?

Inside factories, M2M mainly uses Modbus and OPC UA, utilities also use DNP3, while over cellular and LPWAN networks MQTT, CoAP and LwM2M are common. The choice of M2M protocol depends on energy consumption, data volume and whether the device also has to be managed remotely.

Will my M2M device still work after 2G and 3G are switched off?

An M2M device that only supports 2G or 3G loses its connection as soon as the provider switches that network off. In the Netherlands KPN switches off 2G in December 2027 and the other operators are also retiring their old networks, so replace such modems in good time with LTE-M, NB-IoT or 4G.

How do I secure M2M communication?

You secure M2M communication with unique passwords per device, a private APN or VPN, encryption with TLS or DTLS and regular firmware updates. In addition, every M2M device belongs in the asset inventory and in a separate network segment.

📌 In summary

M2M is the automatic exchange of data between devices that has enabled telemetry, process control and meter reading for decades. Standards such as oneM2M, LwM2M, NB-IoT and LTE-M made M2M more open and more energy-efficient, and IoT builds on it with the cloud and analytics. For OT managers, the 2G and 3G switch-off and the security of unattended devices are the main points of attention.

M2M is the quiet backbone of industrial automation: if you inventory, modernise and secure your M2M connections, you lay the foundation for reliable IIoT applications.