Sending a text message on a mobile phone does prompt that it cannot be delivered.

The usage of sending and receiving SMS overseas is as follows:

1. Send the mobile phone number to Chinese mainland: directly enter the mobile phone number;

For example, in the United States, send short messages to domestic users of 186.

2. Method of sending international short messages in China or sending short messages to other countries or regions in the state of international roaming: 00- country code-user number;

For example, in the United States, send a short message to 876 ... American users and enter "+1876 ..." on the mobile phone.

"+"is an international universal access code, and "1" is an American code.

According to the above situation, I suggest you check whether the sending method is wrong.