Why can’t I use international roaming in Japan after I applied for it in China?

1. The mobile phone mode is not supported locally;\x0d\2. There is no mobile cooperative network provider in the area;\x0d\3. The data roaming of the mobile phone itself is not turned on. \x0d\\x0d\Roaming refers to the function that the mobile communication system can still provide services to the mobile station after it leaves its registered service area and moves to another service area. \x0d\International roaming means that you can also enjoy a series of services provided by China Unicom abroad, including calls, SMS, MMS, mobile Internet, etc. \x0d\ Starting from June 1, 2016, China Unicom has once again lowered its international roaming tariff standards. Voice involves 130 countries and regions, with an average decrease of 48%. Data involves 116 countries and regions, with an average decrease of 72%, of which 5 yuan The scope of data tariff areas has been expanded from 87 to 112. Users accessing the Internet in these countries and regions can enjoy a 5 yuan package of 3MB/5MB tariff, with a daily cap of 80 yuan. \x0d\In the 2016 Brazil Olympics, Brazil's international roaming data service rates were reduced, and the unlimited package was reduced from 56 yuan/day to 26 yuan/day. \x0d\ Starting from October 10, 2016, China Unicom has included India in the unlimited data package of 56 yuan/day, and also adjusted the voice/SMS roaming rates in India and Nepal. China Unicom's international roaming will also optimize and adjust the previous cap of 80 yuan per day to a cap of 160 yuan on the basis of the original business content.