Net profit was 43.37 billion yen ($481 million) during the July-September period, up from 21.75 billion yen a year earlier, the company said Thursday. Revenue was nearly unchanged at 682.9 billion versus 681.7 billion.

Softbank said profit increased even as sales held steady because of falling costs as its mobile operations became a bigger part of its overall business. Softbank paid less to access the networks of other carriers and its per-unit costs for phones dropped as overall shipments increased.

Softbank, which also runs major web properties such as Yahoo Japan and a large stock-trading site, said lower online sales also meant lower expenses.

The upstart carrier is the smallest of Japan's big three mobile companies, but has aggressively undercut rivals with cheap calling plans and introduced flashy ad campaigns with major stars. It has also secured exclusive rights to hit products like the iPhone from Apple, which is well suited to checking the Internet and so boosts income from data charges to customers.

As a result the company has seen its mobile operations, among its most profitable, become a bigger part of its business. Its cellular business brought in about 57 percent of operating profit over the first half of the current fiscal year, compared to about 48 percent a year earlier.

The company's shares ended unchanged at 2,100 yen in Thursday trade before earnings were announced.