I am sing Arduino Mega 2560 to send an SMS to a stored phone number. The problems is that the message is sent in Chinese. I have tried to change the language in Preferences menu but nothing changes for this.
How can this be solves?
What's so strange about Chinese? It's the most common language on the planet, 3x as common as the next one, and that's not English either.
Is it actually Chinese translation of the message, or is it just a mess of strange characters that look like they might be Chinese?
I have tried to change the language in Preferences menu but nothing changes for this.
Do you mean the Arduino IDE's Preferences menu? That only affects the language of the text in the GUI interface of the Arduino IDE. It will have absolutely no affect on your code.