You are not required to make work calls on your cell phone or other personal devices. However, RingCentral can be used on these devices if you wish.
In fact, you can use a tablet, laptop, or desktop computer to access RingCentral. It is that versatile!
The good news is if you do set up your cellphone to accept work calls, you can set your work hours. Once you are off work, so is RingCentral on your cell phone, so no after-hours calls!