I have found the integration from Skype and Teams to Skype for Business to be a bit problematic.
The biggest item so far seems to be the inconsistent nature of originating a conversation from Skype or Teams to a user on Skype for business. In most cases - the Skype for Business user is not recieving notifications at all.
If the Skype for Business user initiates the conversation things tend to work much better. The recipient in Skype or Teams recieves the notification, and once the channel is opened, they work as expected.
Is this the same experiance others are having as well?