No more on-site phone system.
With a hosted system, your devices are integrated and operate on one platform.
Using the UC client is great for those who work from home! Giving you the option to receive all your calls without the need of a physical phone along with many more features.
Using the mobile is great for those on the road, or just want another way to be reached. Having the mobile app allows you to make and take phone calls from your cell phone with the appearance of calling from the office, never using your personal.