I have picked up a new smartphone and installed Textra and made it the default app. I thought I was getting messages until I saw a notification show up and was like huh. why didn't that show in Textra. saw in your help about messages not showing and why you thought. I think your thinking is wrong and you should incorporate RCS in your Textra. thus is why and may help explain the RCS Advanced messaging on the newer phones. See http://www.androidauthority.com/google-jibe-android-rcs-client-675512/