I'm not seeing all the contacts that most of my teammates are seeing

Ringio data is cached locally on your computer.  If you have high call volume, you may need to clear the cache of the application by clicking on the version number at the sign in screen to force a refresh of your data.

To get to the sign in screen if you enabled auto-sign in: Click on your name next to the "Taking calls" button in the top right corner. Then you can click on Sign out to get to the screen.  Then follow the below screenshot.