The mobile phone receives a short message from a mobile phone number with a +86 in front of it. What does this mean?

+86 is the international area code of China. Adding (+86) to domestic mobile phones is the same as not adding, but you have to add +86 to call back from abroad, otherwise you can't get through. International telephone area code, that is, the code assigned to countries by the International Telecommunication Union according to the E. 164 standard. All numbers are prefix numbers, which means that these numbers are used to "dial" the destination country. The international area code related to China is: China +86 China Taiwan Province Province +886 China Hongkong +852 China Macau +853.