Conference call between Skype for Business & Skype
Inside Microsoft family, is completely absurde that skype users and Skype for business user can´t encounter an completed compability envirnoment.
Two SfB user's and one skype, it is no possible.
One skype user and one SfB user, add button desappear.
My organization subscribe recently O365 product, and make several conferences with external investors.Obviously can´t advice O365 product to anyone.