Why can iPhone send text messages to ipad?

It is caused by logging in to the same ID account and opening iMessage. If you want to turn it off, take the Apple 7 mobile phone as an example.

1. Open the Apple 7 phone interface and click to enter the Apple 7 phone settings page.

2. After entering the Apple 7 mobile phone setting interface, click enter information.

3. After entering the information interface of Apple 7 mobile phone, you can see that iMessage is on at this time.

4. Click the "Close iMessage" button, and you will not receive the message on the iPad.