au launches Second Number service for single-device dual numbering

KDDI and Okinawa Cellular have launched a new service called "Second Number" for au smartphone users in Japan. Available as of August 4, 2026, the service allows users to manage two separate phone numbers on a single device by utilizing eSIM dual-line standby capabilities.

The service is designed to enhance privacy and organization by allowing users to separate their professional, personal, and social media registration needs. For a monthly fee of 550 yen, users can add a secondary number dedicated to voice calls and SMS. The service includes the "Denwa Kihon Pack (V)," which features tools such as nuisance call blocking and answering machine services to mitigate security risks and unwanted solicitations.

Additional features include the ability to select specific last four digits for the number through the "YOU-sen Bango" option. Users can manage their contact information exposure more effectively without the need to carry two separate devices or maintain two full service contracts.