To enable a feature where Skype calls you when joining a meeting, there is minimal set up. All that is required is a direct number to reach you, set EXACTLY in this format: +1 (111) 222-3333
Example: Screenshot for Des Moines corporate office work number. But any can be populated. Mobile is grayed out because we usually fill that out for you.
If you use different rooms/phones, I suggest you leave "Before I join meetings, ask me which audio device I want to use" checked. I personally do most of my meetings at my desk, so I have it unchecked to save me a prompt when joining. Below shows my preference of calling my desk as such:
Now when the calendar reminder pops up, you can click Join Online and the meeting will just call you and begin connecting.
Note: If you are ever prompted to enter a meeting PIN, it is the same as your access code.