Testing conformance to a specification can give confidence that an implementation supports the functions defined in the specification and will also, if the tests are well defined, interoperate with other implementations. If a specification has no optional features, then conformance testing alone will give reasonable assurance that different implementations will interoperate.
However, many communication protocols have characteristics that are conditional upon support of optional features and it is possible that different implementations support different sets of features or similar features in different ways and so may not interoperate. It is therefore useful to demonstrate the interoperability of equipment. Interoperability testing also, by its very nature, tests a complete protocol stack rather than testing each component in isolation, as may be the case with conformance testing.
Interoperability testing is usually performed in the development phases of a technology and can be very useful in both testing the equipment and the standard specifications that are being implemented, whereas conformance testing and certification is usually performed on products that are being introduced to the market.
ITU-T Recommendations aim to ensure the interoperability of products produced by different vendors. Conformity to ITU standards does not imply interoperability of equipment, services and systems but significantly increases the probability of interoperability. In accordance with the Action plan
(Council-12) decision to implement Resolution 76
(WTSA-12), ITU organizes and facilitates Interop events in order to test and ensure interoperability of products and services of different manufacturers. This activity forms part of ITU's Conformance and Interoperability (C&I) activities.
Services offered by ITU for Interop Events:
Local arrangements (arranging sites with hosts, shipment, hotels, networking opportunities, visa support, etc.), Logistical arrangements (registration/payment, legal aspects (NDAs), etc.)
IT support, test bed, test session scheduling, etc.
Promotion, media involvement, press releases, event website, inviting prospective customers, etc.