First we will make sure Voice is set to follow your working hours set in Google Calendar.
1. Navigate to your Google Voice app
2. Select the "hamburger" icon on the top left corner of the app
3. Scroll down until you see the "Do not Disturb" section, select "Calendar"
4. Make sure both “Follow Working Hours” and “Follow out of Office” are set ON
Part 2 - Setting Work Hours
1. Navigate to Google Calendar
2. Select the Settings cogwheel in the top right corner of the Calendar window, on the drop down menu also select "Settings"
3. From the list of settings under the "General" tab, select "Working Hours & Location"
4. With Working hours & Location selected, you are able to either completely turn off your work hours and have your phone freely ring, or set periods of time for your phone to ring on certain days