Why can't I send a text message to America?

00 1+ the area code of the other party's area (go to zero)+the phone number of the other party should be enough.

If the other party is a mobile phone, you don't need to add the area code. 00+ country code+mobile phone number will do. However, there should be no zero before the mobile phone number. If the first digit of the other party's mobile phone number is 0, it is usually necessary to remove 0 from O.