NTT DoCoMo has recorded its first weekly slide in the number of subscriptions to its I-mode wireless internet service.
The Tokyo carrier counted 40,132,000 subscriptions to I-mode on 7 December, a drop of 12,000 compared with the total on 30 November.
Cancellations of delinquent accounts that are made at the beginning of each month are to blame for the fall, said Tomoko Homma, a spokeswoman for NTT DoCoMo, adding that she expected the company to end December with net I-mode subscriber growth.
The fall comes after a sharp drop in the number of net new subscribers the carrier has been able to attract to the I-mode service as penetration among its user base approaches 89%.
Subscriber growth averaged just over 300,000 users per month in the six months to October, but dropped to 129,100 in November, according to data from the Telecommunications Carriers Association.
That fall mirrors a drop in net new voice subscriptions, which were running at around 185,000 for the same six-month period and dropped to 63,400 during November.
In contrast, KDDI's Au unit has been enjoying higher than normal new subscriptions and was the only one of Japan's four cellular carriers to record a rise in its voice and wireless internet market shares during November.
Despite the drop, I-mode still accounts for almost 60% of Japan's wireless internet subscriptions. The Ezweb service offered by KDDI has 14.4 million users for a 21.4% share, while Vodafone KK's Vodafone Live service has 12.7 million users for a 18.9% share.
Martyn Williams writes for IDG News Service