Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Try installing the 'Google Duo' app on your phone, and then have your friend with the S6 do the same. It's a reliable video calling app, and it's not too intrusive, basically that's all it's designed to do so there's not a lot of bloat:
https://play.google.com/store/apps/details?id=com.google.android.apps.tachyon&hl=en