au (KDDI)

KDDI operates Japan's au mobile brand — one of the three facilities-based carriers that define the Japanese market alongside NTT Docomo and SoftBank. The company formed in 2000 from the merger of DDI Corporation and KDD, inheriting decades of telecommunications infrastructure and a customer base deeply accustomed to Japanese-specific mobile services. Japan's mobile ecosystem has historically been more vertically integrated than Western markets, with carriers playing a larger role in device certification, content distribution, and payment services than their counterparts elsewhere. KDDI has leaned into that model, building au Pay, au Hikari fixed broadband, and JCOM cable under the same corporate umbrella.

The My au app and web portal manage data plan subscriptions, bill viewing, contract changes, device upgrades, and au Pay wallet top-ups. eSIM issuance for au subscribers requires an authenticated session in the app and a backend provisioning flow that communicates with KDDI's SIM management infrastructure — a process that stalls completely during platform outages. Au's 5G network rollout has expanded across Japan's major urban centres, and KDDI has invested heavily in sub-6GHz spectrum for nationwide coverage depth. The July 2022 network failure — which disrupted service for over 35 million customers for more than 86 hours — was one of the most significant carrier outages Japan had ever experienced.

Network problems at KDDI manifest in ways that go beyond simple call drops. Voice calls fail while data appears to work, or data stalls while voice is unaffected — a reflection of how modern carrier-grade networks separate voice and data path engineering. The My au app returns server errors during account lookups, plan change requests fail to submit, and au Pay transactions decline even when the account has sufficient balance. Emergency eSIM requests — for customers who have just received a new device — queue indefinitely when the SIM provisioning backend is under pressure.

Outage.gg tracks au KDDI network and platform status using community reports from subscribers across Japan. If your au service is experiencing dropped calls, data problems, or My au is throwing errors, the live status page shows the current picture from users across the country.