Business Hours
Setting business hours will allow the phone system to properly route calls based on whether you're in the office (Work hours) or not (After hours). Calls received After Hours will not ring your phone and instead will go straight to voicemail. The behavior for calls during and after hours can be adjusted but it is important to note that the default settings will not allow you to receive any calls during any period set as After Hours.
Business hours can be set within the Settings menu, under the Call Handling tab. Look for the link that states Edit schedule.
You'll receive the following screen as a popup window. The hours you set here should be the times that you will be accepting calls. Generally, this will line up with the times you clock in and out of work. If the hours will be the same Monday through Friday, you can set the hours on just one day, then select the dropdown that says Apply to and select All Weekdays to apply those same times to the other four days.