1. China Mobile, China Telecom, and China Unicom are the three major telecommunications companies in China. Their mobile phone numbers usually start with 13, 15, 18, or 17. However, international callers must enter the country code +86 before the phone number.

2. To call a Chinese cell phone from within China, you do not need to add the +86 country code. theless, when calling a Chinese landline from inside the country, you must first dial the area code followed by the phone number.

3. The Chinese government requires all new mobile phone users to register their phone numbers with their real names and identification numbers. This system is called the “real-name registration” policy. If you are a foreigner, you will need to show your passport when registering your Chinese phone number.

4. Some Chinese mobile phone numbers also have unique codes that indicate the location of the user. For example, phone numbers that start with 139 or 138 are often registered to users in Beijing. Furthermore, phone numbers with the prefix 189 are usually registered to users in southern China.

5. You do not need to add any prefix when sending a text message to a Chinese phone number. Chinese mobile phone numbers are usually 11 digits long, and their format is XXXX-XXXXXXXX or XXXXXXXXXXX. The first four digits represent the area code.

In summary, the prefix that should be used before a Chinese phone number depends on the country you are calling from. However, when sending a text message to a Chinese mobile phone, no prefix is needed. Additionally, since China has a “real-name registration” policy, new phone users must register their numbers with valid identification.