Softbank Mobile revealed today it gained 332,600 net new subscribers during September, the most of any Japanese cellco for the sixth month in a row. The company said it had enjoyed strong sales of the Apple iPhone 4 smartphone, of which Softbank is exclusive provider in the country. Softbank added a total of 1.6 million net subscribers in the six months ending September, a record for a fiscal half. Rival cellcos NTT DoCoMo and KDDI added 109,400 and 91,000 net new users respectively during September, and bringing up the rear eAccess added 68,500.