Is the content received by the mobile phone power-on SMS text?

If you send her a text message, she will receive an unread message and open it to see what you sent. If you don't edit the content and send it over the air, she can only receive your phone number and know it's from you. If the other party has an unread message reminder, the other party's information light will light up to remind her that there is a message coming.

If you send some symbols, some garbled codes may appear on other mobile phones.