HATS Conference(Harmonization of Advanced Telecommunication Systems) has established in 1988 in order to secure the interconnectivity of advanced telecommunication equipment and system that connects it with the network such as ISDN by MIC(Ministry of Internal Affairs and Communication, at that time MPT：Ministry of Posts and Telecommunications), HATS activates to understand and resolve the problems of interoperability between those equipments with cooperating users, makers and telecom carriers.
Now, HATS is organized to activate to cooperates by telecom carriers and manufacturers.

HATS has been defined the test guideline to confirm the interoperability between the test target devices and interoperability has been confirmed by testing under guideline procedures.
Also, HATS has been making a international contributions by feed back to ITU and/or TTC through the HATS actual test result problems such as vagueness of the description of the standard.

At the start of HATS activities, the target devices were the equipment for the ISDN, after that HATS is planning to expand the target to the LAN/Internet and multimedia equipment. We plan to test the devices and systems for the NGN, now.