On May 29, 2025, Japan's Ministry of Internal Affairs and Communications (MIC) issued amendments to Regulation No. 54 of 2025 to the Telecommunications Terminal Equipment Regulations. The amendment imposes emergency cross-carrier roaming requirements for Internet Protocol (IP) mobile phone terminals, such as smartphones, to enable users to temporarily access other carriers' networks in the event of an emergency. The amendment will enter into force on October 1, 2025. A two-year transition period applies to IP mobile phone terminals that meet any of the following criteria:

• Have obtained certification in accordance with technical standards or have submitted a self-confirmation of compliance with technical standards;
• Special circumstances that may be considered with the approval of the Minister of Internal Affairs and Communications.

Click on this link to view the original text of MIC Regulation No. 54 of 2025.