These three countries were chosen because they were representative. Before I went to Thailand, I was well prepared because it was my first time going abroad. I bought mobile phone cards online in China, and when I arrived in Bangkok, I could buy them at the airport, SE Ven-Eleven and other convenience stores, which were cheaper than those in China.
​Buying a Pr phone cards is a lot more expensive in Japan. Japanese airports can rent a portable WIFI, 10000 yen (about RMB 500 yuan), back when marking it in the recycling bins in the airport, because Japan has a special rate for foreign visitors. At home, buying a mobile phone card is cheap. A big Gai 50 yuan will do the trick.
Australian mobile cards can also be bought domestically, but be sure to open them. If BUY IN Australia, WANT ONESELF OPEN, English IS GOOD, THE ADDRESS THAT SHOULD FILL IN PLACE WHEN FILLING IN THE ADDRESS, CANNOT WRITE HOME. In addition, some domestic telecom operators offer free roaming service for five or 10 days abroad. However, the service cannot be used in foreign apps such as Google Maps navigation, and domestic mobile phones are also not allowed.