In the latest version of the client (15.5.6354.2) you removed the possiblity to create ad-hoc conference calls *from the client*. It used to be that you pressed the "conference" button when in a call and that created the conference and took you to the "conference" tab where you could easily add more participants. Now to create a conference it *must* be added to the calendar, and participants must call in (ie: they can't be added). This is a hassle. You basically removed the possiblity to do ad-hoc conferences. Please add it back.