When creating a Lync meeting while offline, it can sometimes request that you sign into Lync to progress with creating. This can be an issue for some people if they do want to work while offline. However you can fix this issue if you follow the steps below.
Within outlook you can go to the menu bar at the top and chose New Items > Lync meeting. Once this is done it brings up the meetings page, you can then go to the ‘Meeting Options’ tab.
By default, when the box appears it will automatically be set to ‘A new meeting space’. If you change this to ‘My dedicated meeting space’, you will see everything else grey’s out.
Then click ‘Remember Settings’ and this should let you create a Lync meeting while offline.