How does Apple's mobile phone send group messages to strange numbers?

In fact, it is very simple to send text messages in groups on phone4. After editing the content, add it to the recipient. After each addition, click the blue and white+icon, and you will enter the contact. If there is a contact number, add it. If it is a separate numeric number, click Cancel. At this time, the screen will return to the new SMS recipient column and enter the number again (it doesn't matter if you can't see the cursor for a while, the next line of the contact has been blocked by the content column, so you can see it many times by clicking on the content and recipient columns respectively).