Can we use a VoxSun phone at home?

Yes, one of the advantages of VoxSun being a phone system in the cloud is that you can use your phones anywhere in the world, as long as a high-speed, stable, and unrestricted Internet connection is available.

Keep in mind that, unless you have a VoxSun router installed at home, you will not benefit from ActivVoice QoS technology so call quality might vary when there are network transfers happening.
If you're using your own router, you will also need to make sure that the SIP ALG function is disabled on it, as most routers enable it by default and this causes stability variations for IP phones.