KDDI Corporation (KDDI Kabushiki Gaisha) (TYO:9433) is a Japanese telecommunications operator formed on October 1, 2000 by the merger of DDI Corp. (Daini-Denden Inc.) and KDD (Kokusai Denshin Denwa) Corp. (itself a former listed state-owned enterprise privatized in 1998) and IDO Corp. Its headquarters are located at the Garden Air Tower in Iidabashi, Chiyoda-ku, Tokyo.

KDDI uses the "au by KDDI" brand to provide mobile cellular services. ISP network services are provided under the au one net brand, while "au Hikari" is the marketing name for long-distance and international voice and data communications services, as well as fiber-to-the-home (FTTH) services. The brand name for the ADSL broadband service is "ADSL One" and the brand name for the copper IP phone is "Metal Plus".

The four stages of KDDI certification:

1. Pre-IoT stage: To verify the most basic registration function of the prototype, testers need to check whether the basic parameters such as APN reported by the terminal are consistent with those claimed by the questionnaire
2. IoT-L stage: testing in KDDI laboratory, including field testing, etc., the testing time is 2~3 weeks, and you need to make an appointment with KDDI laboratory in advance.
3. IoT-F stage:
   • Verification of VoLTE, ETWS, and SMS modules
   • It is divided into two parts: simulator and field test
   • If necessary, you can apply for a Waiver from KDDI
4. Submit a report to get a TA
   • The results in the test plan can be submitted to KDDI as a final report
   • Final TA is awarded by KDDI