KDDI Corp. said Monday it has found defects in about 320,000 au mobile phone handsets.
KDDI said it will upgrade the software in about 258,000 A5503SA au mobile phones manufactured by Sanyo Electric Co.
The handsets have defective data-management functions and users may have trouble sending and receiving e-mail.
The company also said it will send new batteries from April 7 to users of about 66,500 A5403CA au mobile phones made by Casio Computer Co., as the power may shut down due to battery defects.