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.
This does not work as intended. Even if a user is in Skype for Business only, and I IM them from Teams, it goes nowhere, or they get an email that I'm trying to reach them in Teams.
We really MUST have this in order to start a rollout.
We’re updating our command library all the time, so keep checking the menu in the command box to see what’s new by typing / or @.