NTT Docomo Inc. could offer a cut-price data service for smartphones and tablet computers, possibly in June, as part of a drive to attract new customers, sources said Wednesday.

The mobile phone carrier is also planning to introduce a flat-rate service granting users unlimited voice calls around the clock to people on any of the nation's phone networks.

The new data service would include 10 gigabytes of data for around ¥10,000 per month, and the data would be shareable with family members, the sources said. For a family of four, the cost per person each month would be approximately ¥2,500 — a sharp drop from the ¥4,700/3GB service and ¥5,700/7GB service the company currently offers its customers.