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Can I use an au / UQ mobile SIM card in a SIM-free or used smartphone?

When using a 5G SA-compatible device with a 5G contract

Can I use an au / UQ mobile SIM card in a SIM-free or used smartphone?

It is possible to use it with 4G/5G, but 5G SA network usage is not possible.

To use 5G SA network, you will need to change to a 5G SA contract and change your SIM card.

Procedure

When using a 5G SA-compatible device with a 4G (VoLTE) contract

Can I use au SIM card in a SIM-free or used smartphone?

You cannot use it. You will need to change to a 5G SA contract and change your SIM card.

Procedure

When using a 5G compatible device with a 4G (VoLTE) contract

Can I use au SIM card in a SIM-free or used smartphone?

No, it cannot be used. You will need to change to a 5G contract (change of plan).

Important note

  • From September 1, 2025, onwards, there will be no change fee for procedures done on My au (Web) .

    If the fee becomes charged, it will be announced on the official au website.

    • The fee for procedures at au Style/au Shop is 3,850 yen (including tax).

Procedure

When using a 5G/VoLTE-compatible device with a 5G SA contract

Can I use au / UQ mobil SIM card in a SIM-free or used smartphone?

Operation is not guaranteed. Please change to a 5G/VoLTE contract and the SIM card before using.

Procedure

When using a VoLTE compatible device with a 5G contract

Can I use au / UQ mobil SIM card in a SIM-free or used smartphone?

It is possible to use it with 4G, but you cannot use the 5G network.

When using a smartphone with a 4G (VoLTE) feature phone plan

Can I use au SIM card in a SIM-free or used smartphone?

No, it is not possible. A plan change for the smartphone will be required.

Important note

  • From September 1, 2025, onwards, there will be no change fee for procedures done on My au (Web) .

    If the fee becomes charged, it will be announced on the official au website.

    • The fee for procedures at au Style/au Shop is 3,850 yen (including tax).

For VoLTE/5G compatible smartphones

  • Procedures must be completed at an au Style/au Shop.
  • To change from 4G (VoLTE) to 5G, you can also do the procedure at the customer center.

Contact us

For KDDI Customer Center
click here

Business hours

From 9:00 a.m. to 8:00 p.m. (open all year round) 

For 5G SA compatible smartphones

When using a mobile phone from another carrier

Can I use an au SIM card in a SIM-free or used smartphone?

You can use it by completing the necessary procedures.

For details on the procedure for using an au IC card with a mobile phone from another carrier, please refer to the following page.

Click here for details on the procedures when using a mobile phone from another carrier (in Japanese only)
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  • All of the indicated amounts exclude tax unless otherwise specified.
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