Please follow the below link for procedures and important considerations when using an au IC card with another company's mobile phone.
Make sure to read and understand the information below in "Important considerations regarding usage of non-au mobile phones", and visit your nearest au shop for details about procedures if necessary.
*A "(V)" is appended to the names of rate plans and data flat-rate services for 4G LTE (au VoLTE compatible) Android™ smartphones.
*If changing the contract between WIN/LTE/VoLTE or switching between an LTE Single (data communication terminals, tablets, etc.) and Dual (smartphones) contract without purchasing a mobile device, a contract change fee of ¥3,000 will be charged.
To use the Internet on a non-au Android mobile phone, you will need to sign up for LTE NET for DATA and then set up an Internet connection. Please note that you cannot connect to the Internet via LTE NET when using a non-au mobile phone (Android devices).
Customers who use packet communications on a non-au Android mobile phone must set the access point. For details see the LTE NET for DATA page.
With regard to rate plans, discount services, etc., the same fee structure used for au mobile phones is also used for all non-au mobile phones. Please note that if you are not signed up for a data (packet) flat-rate communication service, you may experience unexpectedly high packet communication fees. It is therefore strongly recommended that you sign up for a data (packet) flat-rate communication service. Also, please note that the LTE Single (data communication terminals, tablets, etc.) rate plan and discount service is not available to non-au mobile phone users.
Repairs and other after-sales services for non-au mobile phones are not handled by au. For information on how to handle repair issues, contact the company from which you purchased the device.
Except in cases of willful or gross negligence on the part of au, au shall bear no responsibility for any loss, damage, or trouble that may result from using an au IC card in a mobile phone or other device sold by another company.