The telephone number in Japan consists of three parts: (external office number)+(external office number)+(number). You don't need to dial an out-of-office number to make a local call. Even if you dial an out-of-office number, you will be connected. Don't be too nervous.
To make an international call, you can dial directly or get through the operator. There is a metal phone in the hotel that can be paid by credit card. If you want to make an international call in the city, you must look for the gray phone marked "International Call".
After finding a public telephone that can make international calls, first enter the numbers of international telephone companies 00 1(KDD), 004 1(ITJ) and 006 1(IDC), although they belong to three telephone companies, the charges are basically the same.
Secondly, dial (country code)+(domestic telephone number). By the way, the area code of China is 86. In addition, dial "0" before making domestic long-distance calls. When you want to make a collect call, you need to go through the operator instead of dialing directly. If it is KDD, you can use "005 1" to make a phone call, and the operator can talk in Japanese and English.