How to add the telecom area code?

Telecom's mobile phone number used to be the same. In other words, as long as it is China's mobile phone number, it will always be in front of it. Area code refers to the telephone area code commonly used in the administrative areas of major cities in the world, which is mainly used for domestic and international long-distance telephone access. For example, Chinese mainland international area code 86, Beijing area code 0 10, Guangzhou area code 020 and so on. When using domestic long distance calls, dial 0 before the area code. It is worth mentioning that people often confuse concepts and mistakenly think that there is a 0 in front of the area code itself. In other words, because 0 is the only long-distance access code in China, it is often used side by side with the following area code, so it has become a habit. In fact, when calling back to a domestic city from abroad, the local international long-distance telephone access code is added after the China country number 86, and there is no 0 in front of the city area code. For example, the area code of Chengdu should be 28, not 02.