Message forwarding not available on iOS 8.4 iPhone iPad iOS 12.1
I am able to send and receive messages using iMessage to people with Android phones no problem on my iPhone.
There are some people who have Android phones that I can text with my iPad iMessage no problem. Others tell me they don’t have iMessage installed when I attempt to text them from my iPad.
My iPhone, a 4S with iOS 8.4.
My iPad, an Air 2 with iOS 11.
Both have cellular on different data lines.
According to some documentation there is a setting for forwarding iMessage. But I don’t see it on my iPhone or iPad under Settings.
So how do I enable the ability to text the same people on my iPad as work on my iPhone?