It looks like some people in the thread below have figured it out — we actually have this. You can start a chat both ways; the system will automatically recognize if this person is on Skype for Business or on Teams.
Thanks and let me know if you have any questions.
SuphatraAnil Kumar Singh commented
This only works if skype is online not true for onprem skype with hybrid
1 voteAnil Kumar Singh shared this idea ·