Currently to silence just the ooma office mobile app (and not my cell phone) I need to log into ooma, and disable the mobile app when I don’t want it to ring. I do the same thing to turn it back on. The hassle has meant that I’ve uninstalled the app rather than deal with my phone buzzing after work and on weekends.
Add a setting in the mobile app to toggle the ringer and call notifications on and off. Then I will actually start using the app.