KDDI Corp. appears to have benefited the most from the mobile phone number portability service introduced Oct. 24 to allow people to switch phone companies without changing their numbers.

KDDI, which operates the au mobile-phone service, said Wednesday that it had a net 200,500 new subscribers in October, to give it a total of 26.6 million customers at the end of the month. KDDI is the second-largest carrier in terms of market share.

Market leader NTT DoCoMo Inc. saw its subscribers increase by 40,800 to 52.1 million in October. The third-largest carrier, Softbank Mobile Corp., a unit of Softbank Corp., said its subscribers increased by 23,800 to hit 15.3 million.

After number portability was introduced, KDDI said it had a net gain of more than 102,000 subscribers for the last week of October. Softbank fared badly, with a net loss of 23,900 subscribers in the last week. NTT DoCoMo did not provide any figures.

Even before the introduction of the number portability, KDDI was getting more subscribers -- including people switching from its rivals -- as it is offering improved music downloading and a search engine through Google Inc.

In September, subscribers to KDDI's mobile phone service increased by 160,800 from the previous month, compared with a gain of 126,300 at NTT DoCoMo and 23,400 at Softbank.

Softbank Mobile introduced a low-priced phone service the day before number portability began. However, it had to stop processing applications twice over the first weekend due to the overloading of its computer system.