DOCOMO Reports Malfunction of sp-mode Service


TOKYO, JAPAN, December 21, 2011 ---NTT DOCOMO, INC. reported today that its sp-mode service malfunctioned between 12:22 and 14:25 on Tuesday, December 20, 2011.

Due to this problem with the communication equipment, the email addresses of some customers using the service were reset with incorrect addresses.

The company deeply apologizes to its customers for any inconvenience caused by the malfunction.

  1. Details of Service Malfunction
    • When some users checked their registered address, they found that the address had been changed.
    • People who received an email from a sp-mode user saw the address of another sp-mode subscriber as the sender’s address, and if they replied, their mails were sent to that address.
  2. Reason for the Problem and Details
    • At 12:22 on December 20, an interruption in a transmission line caused a disruption in the sp-mode server in the Kansai area, resulting in the server’s incorrect processing of telephone numbers and IP addresses.
    • The disruption was recovered by implementing capacity restrictions at 14:25, but according to customer reports, thereafter it appears that some customers experienced problems with their mail addresses being changed.
    • Due to the sp-mode server’s automatic self-correcting function, DOCOMO believes that the problem was resolved by around 18:00.
    • As a precaution, DOCOMO has advised customers to turn their smartphones off and on one time. In addition, the company has reset related packet switching equipment as part of final efforts to fully resolve the problem.
  3. Customers Assumed to Have Been Affected
    A portion of customers using the sp-mode™ service were affected, numbering about 100,000 subscribers. As of 07:30 on Wednesday, December 21, 108 customers had contacted DOCOMO to inquire about matters related to this problem.
  4. Response to Customers
    DOCOMO will contact individual customers who were determined to have been affected by the problem. As a result of the incident, DOCOMO temporarily suspended the operation of certain sp-mode services that possibly could have been affected (see attachment).
  5. Effort to Prevent Similar Problems
    DOCOMO will comprehensively reevaluate the processing capacity and procedures of its overall network. Immediate actions for preventing similar problems are as follows:
    • Increase the processing capacity by adjusting the user administration server.
    • Improve the IP-address issuing protocol for smartphones.

(Attachment) Temporarily Suspended sp-mode Services

NTT DOCOMO is a world-leading mobile operator that is in transition into an Integrated Service Company placing mobility at the core. The company serves over 59 million customers in Japan via advanced wireless networks, including a nationwide 3G network and one of the world’s first commercial LTE networks. Leveraging its unique capabilities as a mobile operator, DOCOMO is a leading developer of cutting-edge technologies for NFC mobile payments, mobile GPS, mobile TV, intuitive mobile assistance, environmental monitoring, smart grids and much more. Overseas, the company provides technical and operational expertise to eight mobile operators and other partner companies. NTT DOCOMO is listed on the Tokyo (9437), London (NDCM) and New York (DCM) stock exchanges. Please visit for more information.

sp-mode is a trademark or registered trademark of NTT DOCMO, INC. in Japan.
sp-mode is only available to subscribers in Japan.

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