The July 2 Communication Failure and Our Response
On July 2, 2022, starting at about 1:35 am, KDDI experienced a significant communication failure.
We deeply apologize for the inconvenience for those affected.
As a telecommunications carrier, supporting social infrastructure
and providing stable service, we take such incidents seriously.
We have implemented measures to try to prevent recurrences and will make every effort to foster smooth operations going forward.
General Outline of Communication Failure
|Affected time||From July 2 (Sat) 1:35 am (JST)
to July 4 (Mon) 3:00 pm
(Total : 61 hours 25minutes)
|The number of affected customers||Voice
Calculated based on differences of the number of calls and average calls per person between at normal time and at communication failure
|7.65 million or more
Difference of the number of location registration for 4G/5G services between at normal time and at communication failure (Maximum value)
Impact on Corporate Customers
Industries and Infrastructure
Delivery status updates
Contact with delivery drivers
Connected car services
Weather data collection
ATMs outside of banks
Wireless transceivers in airports
IC cards for buses
Overview of Communication Failure and Response
Failures caused by maintenance work cascaded
Occurrence and Cause
Overview of the Communication Failure
Large number of location registration request signals generated due to incorrect router settings.
VoLTE nodes and subscriber DB nationwide were congested.
Communicationflow at a normal time
System configuration diagram is as follows.
To make voice calls (VoLTE), devices register locations, then outgoing and incoming calls become possible.
(1) Congestionat VoLTE Nodes
- Router incorrectly configured during maintenance of nationwide transport network router in Tama. The location registration※ request was abandoned, rapidly triggering numerous retransmissions in network and Tama’s VoLTE nodes became congested.
- VoLTE nodes at other sites became congested because distributed processing was performed via the nationwide transport network.
(2) Congestion atSubscriber DB
- As the VoLTE nodes and mobile network equipment (PGW※) authenticate at the subscriber DB each time, it was retransmitted, causing excessive signals flows and subscriber DB became congested.
(3) VoLTEnode disconnection (recover)
- In order to reduce congestion on subscriber DB, flow rate control was implemented, but congestion was not eliminated. Some VoLTE nodes continued to send excessive signals, so high volume on subscriber DB continued.
- The VoLTE nodes (6 out of 18 nationwide) were separated, and thus eliminating retransmission from devices.
Overview of Occurrence and Cause
Failure occurred due to lack of consideration for congestion caused by an incorrect setting.
|During maintenance work||Misconfigured router route|
|Get larger scale||Insufficient anticipation of congestion control|
|Prolongation||Recovery work procedure in a congested condition|
Recurrence prevention measures
Improving Quality and Services
Building a cross-organizational system, granting highest priority to network stabilization and improvement of customer relations
Recurrence prevention measures
Measuresand implementations are in progress for each factors
|implementation details||implementation period|
|Get larger scale|
|Announcement for customers||Improvement of information disclosure to customers; timely and appropriate announcements||Partially implemented on July 14, 2022, the rest of parts planned by the end of September2022|
Refunds to customers
Details of refunds
Please select one of the communication services you use.
Schedule for sending SMS regarding information on refunds
KDDI has completed sending SMS to customers who are eligible for a refund.
(Click here for how to check your refund.)
There will be no link URL or request for customer information in the body of the SMS sent by KDDI regarding the refund. Please beware of fake e-mails and SMSs purporting to be from our KDDI.
Phone number from which SMS sent from KDDI will be sent
Depending on the receiving app, the following will be displayed. These phone numbers are connected to KDDI's customer center.
|au||157||Information from KDDI|
Customers using +Message
The sender of the message may be displayed as "157" in addition to the above "Information from KDDI" depending on the model you are using.
Customers using mobile phones
If a message received by the +Message app is only partially displayed, the full message can be viewed by clicking on "See More".
Information on refunds
Since povo2.0 has a basic usage fee of ¥0, KDDI will give customers a data topping (1GB/3 days) in lieu of a refund.
Schedule for sending e-mail
KDDI has completed sending the e-mail regarding the data topping (1GB/3 days).
Please enter the "promo code" in the body of the e-mail using the povo2.0 app to redeem.
KDDI will not ask you to enter any customer information in the body of the refund e-mail. The "promo code" is included in the body of the e-mail and KDDI will not ask customers to confirm the "promo code" via a URL link. Please beware of fake e-mails and SMSs purporting to be from our KDDI.
How to receive data toppings
To receive your data topping (1GB/3 days), you will need the promo code that you receive via e-mail.
Check here for information on how to redeem your promo code.
In addition to the policy refund, an apology refund will be issued as follows.
Refund based on Terms and Conditions
2.71 million (KDDI),
70,000 (OKINAWA CELLULAR)
Customers who could not use all communication services consecutively for more than 24 hours, or those who were in the same level of situation, during the communication failure (customers who have made a contract for voice services only)
Subtraction of the amount equivalent to 2 days of basic charge of subscription plan from amount billed
Refund with apology
35.89 million (KDDI),
660,000 (OKINAWA CELLULAR)
All customers who have made a contract for smartphones, feature phones, and Home plus phone services(Fixed services with VoLTE) , during the communication failure
Subtraction of 200 yen (excluding tax) from amount billed
Customer Notice for Refund
- July 29
- Announcement of refund approach (Refund on terms and conditions / refund with apology)
Post the announcement on our website
- From July 30
- Notice of refund approach in newspapers
- From mid August
Eligible customers confirmed
SMS notices to eligible customers for refund
We will not request sensitive information and not include application links in SMS notices.
- From September
Subtractions will be applied to bills
We are implementing company-wide efforts
to prevent similar future occurrences
and continue to provide reliable communication services
by taking appropriate measures to support increasing data traffic
in this 5G/Beyond 5G era.
The KDDI Group, united as a team,
will help mold a truly connected society.
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