Do I need to add any number before sending a text message? Who can help me?

The code for China is 086. If both parties are China users (regardless of Unicom), you don't need to add anything, just enter 1 1 cell phone number. The default value of country code is +86.

When sending a text message to a foreign mobile phone, you should add the code of that country before the mobile phone number. Specifically, it is "+xy", X is the country code, Y is the other party's mobile phone number, and "+"cannot be omitted.