"The system was designed to provide vital communication capabilities in all circumstances"

Federated Mission Networking[1] has adopted STANAG 4606 Edition 4 as the official standard for secure satellite communications – and Thales's Modem 21 system is already compliant.

Xavier, can you tell us why Thales decided to develop Modem 21 twenty years ago? What were the initial challenges?

Modem 21 was developed to ensure that the French armed forces have the resilient military satellite communication capabilities they need, even in the most demanding and highly contested environments. France had long been aware of the threats posed by offensive jamming and the need for reliable operational communications even in high-intensity combat situations. So the system was designed to provide vital communication capabilities in all circumstances, regardless of the tactical environment and however hard an adversary might try to jam allied systems.

How has Modem 21 evolved since then to meet new military and technological challenges?

Modem 21 has constantly adapted to changing requirements and technologies, and we have supported all the transitions of the last twenty years, in particular the shift to IP communications from traditional circuit-switched technology. At the same time, we have expanded our expertise in security architectures and anti-jamming techniques, and made significant strides forward in terms of the operational flexibility of our solutions. Today, the cutting-edge technologies behind Modem 21 guarantee resilient, high-reliability communications capabilities even in highly contested environments, as recent conflicts have shown. 

The system is compatible with GEO, MEO and HEO satellite architectures, and it's designed to evolve towards the multi-orbit environments that will eventually include LEO constellations and cover virtually all the orbital regimes of military satellite communications. Configurations have also evolved, with Field versions of Modem 21 now available for mobile and deployable ground stations, and Air Compact versions for use on board aircraft.

From a technological standpoint, the system incorporates advanced link protection mechanisms, such as frequency hopping, dynamic data rate and waveform adaptation and enhanced anti-jamming capabilities to maintain service availability in contested electromagnetic environments.

How did Modem 21 and its STANAG 4606 waveform become the industry standard? Can you tell us more about that process?

From the outset, Thales worked closely with international standardisation groups and the defence ministries of allied nations, including France, which acts as the custodian of NATO's STANAG 4606 standard.

We were actively involved in defining and developing the necessary standards and played a major role in a whole range of collaborative projects.

In terms of field operations, we have taken part in the international CWIX exercises (Coalition Warrior Interoperability eXploration eXperimentation eXamination eXercise) that NATO organises each year. During these exercises, more than forty nations and defence ministries work together to validate the interoperability, performance and security of our systems in a broad range of operational conditions. Specifically, our involvement in the CWIX exercises covers satcom, 5G, high-data-rate HF radio, ESSOR radios, PCN, the cloud, and more. Modem 21 has consistently demonstrated its ability to interface effectively with allied communications systems, illustrating its robust performance and technological maturity in real-world use cases.

Today, Modem 21 is already in service or undergoing qualification with several European and allied countries, and provides a solid framework for interoperability between forces deployed on multinational operations.

To guarantee interoperability, NATO sees compliance with FMN specifications as a basic requirement, stipulating that "it is mandatory for Nations providing forces to the NRF/ARF[2]) to prove compliance with FMN Spiral Specifications, and it is highly desirable for other Nations to do so as well.”

For Thales, this means continuously building these requirements for standardisation, security and interoperability into our development cycles.

At the same time, Thales is also maintaining its close ties with the NATO ecosystem through a number of other strategic initiatives. In February 2026, for example, we will be hosting a session of the FMS's Tactical Edge Syndicate (TES), which will be an important opportunity to share insights with partners from across the NATO community, understand real-world expectations and discuss the operational solutions required in the field today and in the future.

All these initiatives, our capacity for innovation and the proven ability of Thales solutions to adapt to new and emerging requirements, explain why our Modem 21 system already complies with STANAG 4606 Edition 4 and FMN Spiral 6, and is recognised as an essential building block for NATO and a key enabler of the sovereignty and interoperability of its Member States.