When you send a message, what determines whether it's an iMessage or an SMS?
I send a message to my daughter, who has a Samsung phone, and it's an SMS (green); when I send to my brother, who also does NOT have an iPhone, it's send as iMessage (blue), and HE DOESN'T GET IT. I want to know how to tell my phone to send SMS to my brother, not iMessage.
iPhone 11