The aviation industry has adopted AMHS (Air Traffic Services (ATS) Message Handling Services) to support ground to ground communications for services such as flight plans and meteorological data. AMHS based systems replace those based on the older AFTN and CIDIN based systems.

Hundreds of AMHS-based systems have now been deployed around the world, with a large majority of countries who have so far made the switch, using solutions from Isode partners that incorporate Isode servers and APIs.


AMHS provides a distributed message switching and storage infrastructure, to enable transfer of ATS messages, such as flight plans, NOTAM (Notice to Airman) and Meteorological information. The AMHS service is accessed by users, using AMHS terminals, and applications (such as Meteorological applications), in order to exchange ATS messages. AMHS Terminals and AMHS Applications connect to the AMHS infrastructure using X.400 protocols.

What Isode Provides

Isode provides servers and APIs used in building an AMHS solution:

  • M-Switch X.400: an X.400 MTA (Message Transfer Agent) that provides the core message switching services and connects to external systems.
  • M-Store: a robust X.400 Message Store for storing messages.
  • M-Vault: an LDAP/X.500 Directory Server which is used to configure the Isode AMHS products and may also provide an independent directory service.
  • An X.400 Client API enabling the development of AMHS client applications connecting to M-Switch using X.400 P3 or to M-Store using X.400 P7. This multi protocol approach allows applications to either directly access M-Switch X.400, or to go via M-Store X.400 if message storage is needed.
  • An X.400 Gateway API enabling the development of AMHS Gateways to AFTN or CIDIN following the specifications in the ICAO SARPs for provision of an MTCU (Message Transfer and Conversion Unit).
  • An X.400 demonstration user agent, Xuxa, a Java GUI to help test and demonstrate and test Isode server products an APIs.

Solutions based on the Isode AMHS products offer a number of benefits including full ICAO SARPs Conformance (Isode's solution is the first to be conformant to the Extended ATS Message Service, and the first to provide a conformant ATN Directory), Fail-over clustering support for all components and Directory based configuration management providing flexible client/server configuration.

AFTN Transition and Co-Existence

As ground to ground messaging moves to AMHS, it is important that full interoperabilitiy is maintained with existing AFTN systems. This is achieved by the use of an AFTN/AMHS gateway, formally known as an MTCU (Message Transfer and Conversion Unit). MTCUs are critical to enabling full connectivity while both AFTN and AMHS are being used. MTCUs are available from Isode partners.

The Extended ATS Service and ATN Directory

AMHS defines two services:

  1. The Basic ATS Service, which provides functionality equivalent to AFTN.
  2. The Extended ATS Service, which provides additional services and functions, including security based on digital signatures; binary attachments; large attachments.

The Isode servers and APIs provide full support for both the Basic and Extended ATS Service. A key element of the Extended ATS Service is use of the ATN Directory. Isode provides a full set of products for constructing an ATN Directory solution.

Further Information

Links to relevant whitepapers:

Needs to be filled in post whitepaper rationalisation.