The aviation industry is adopting AMHS (Air Traffic Services (ATS) Message Handling Services) for provision of ground to ground communication. Isode provides a set of ICAO (International Civil Aviation Organization) SARPS (Standard and Recommended Practices) conformant server products (M-Switch X.400, X.400 Message Store, and M-Vault), to provide an AMHS infrastructure.

X.400 provides an extensive and powerful set of features, and as a consequence, generic approaches to integrate applications are complex. Isode's AMHS Integration Library provides a simple abstraction of the X.400 functionality to meet the needs of AMHS applications. Applications developed over the AMHS Integration Library can be deployed in three ways:

  1. Over X.400 P7, to access the X.400 Message Store. This is useful for AMHS end applications that require storage services from AMHS.
  2. Over X.400 P3 to directly access M-Switch X.400. This is useful for AMHS applications that provide their own reliable storage, and wish to transfer messages over AMHS without the overhead of a Message Store.
  3. Co-resident with M-Switch X.400. This is primarily intended for AMHS/AFTN gateway applications, which need to access X.400 functionality that is not available over P3 or P7. The library provides all of the AMHS side of an AMHS/AFTN gateway, making it very straightforward for a vendor with an AFTN product to offer an AMHS/AFTN gateway.

Deployment Targets

The Isode AMHS Integration library is designed for use by vendors building solutions for the aviation industry, in developing ground to ground applications that operate over AMHS, and for integrating AMHS applications with the AFTN network.

Key Benefits

The Isode AMHS Integration Library offers the following benefits:

  • For developers of AMHS applications, it provides a very simple abstraction, which can be used with new applications or to support existing AFTN applications working directly over AFTN.
  • For AFTN vendors, it provides a simple mechanism to provide an AFTN/AMHS gateway, by abstracting key X.400 and gateway functionality.
  • Although the X.400 complexity is abstracted, the API is designed so that all X.400 services can be selected and modified if required.
  • The API is cross platform - available on both Windows, Linux, and Solaris
  • The API gives access to both basic and extended AMHS services.
  • The API gives access to LDAP and X.500 directory services, to provide simple client lookup and routing capabilities.
  • The same basic API can be used for three different modes of deployment (local; P3; P7)


The AMHS Integration Library can be used in three distinct ways, as illustrated below. In the first architecture, the library connects the application to M-Switch X.400 using P3. This is appropriate for AMHS applications that need to send and receive messages, and deal with message storage as a part of the application.

The second option, shown below, connects to Isode's X.400 Message Store using P7. In addition to sending and receiving messages, this architecture enables message storage, and is appropriate for applications that need the infrastructure to support message storage (e.g., to permit access to a message by a second terminal, in the event of a hardware failure).

The final version of the API is co-resident with M-Switch X.400. This is primarily intended for building AFTN or CIDIN gateways, which require access to X.400 (message transfer) service elements which are not available over P3 or P7. This architecture could be used for general AMHS applications, although Isode recommends use of the P3 architecture for AMHS applications co-located with M-Switch X.400.


Authentication over protocol can use one way or two way password based authentication. When operating over TCP/IP, encryption can be provided by use of IPsec.

Use of Directory

The AMHS integration library provides for directory calls, to enable lookup of X.400 addressing information for AMHS recipients, that can be used to address messages, so that the application does not have to handle X.400 addressing directly. This API can be used of X.500 DAP or LDAP.


The AMHS integration library has been primarily developed to integrate AMHS applications with the Isode server products. Because of its use of the P3 and P7 protocols, applications developed with this library should also work with other conformant servers.

The P3 and P7 protocols can operate either over TCP (RFC 1006) or over a SARPS conformant OSI stack.



'Message Transfer System: Abstract Service Definition and Procedures' [ISO/IEC 10021-4]

X.413 (88)

'Message Store: Abstract-service Definition' [ISO/IEC 10021-5]

X.400 International Standard Profiles

ICAO SARPS Doc 9880 requires conformance to three X.400 profiles: AMH22: AMH23; AMH24. Isode is conformant to these profiles, and the other profiles that these require:

  • IPM: Requirements for Message Transfer (P1): ISP 12062 - 3/AMH22 (MTA to MTA)
  • Common Messaging: Message Transfer (P1): ISP 10611 - 3/AMH11 (required by AMH22)
  • IPM: Requirements for MTS Access (P3): ISP 12062 - 4/AMH23 (Message Store to MTA)
  • Common Messaging Requirements for MTS Access (P3): ISP 10611 - 4/AMH12 (required by AMH23)
  • IPM: Requirements for enhanced MS Access (P7): ISP 12062 - 5/AMH24 (UA to Message Store)
  • Common Messaging: MS Access (P7): ISP 10611 - 5/AMH13 (required by AMH24)


ICAO SARPS Doc 9880-AN/466 Manual on detailed technical specifications for the Aeronautical Telecommunication Network using ISO/OSI standards and protocols, Part II - Ground-ground applications (ATSMHS) 1st Edition.


The AMHS Integration Library is available on Isode supported platforms.