Earlier this year Skype announced to developers that its Desktop API was going to be killed off at the end of 2013. This is an old API exposed a number of the applications internals for use by third-party developers. It was originally offered back 2004 when building an eco-system as an important strategic move for the company.
As a practical matter, within my sphere of activity, the loss of this API basically meant that any hardware that accessed the Skype client would cease to work correctly. That includes products like the Polycom C100S USB speakerphone and the Logitech Conference Cam BCC950 as both of these devices accessed the Skype client to control hook state via the “call control buttons.”