In the case of a VoIP device that currently connects to your router, there shouldn't be any issue with using Winston in line.

If your modem has a designated RJ11 connector for your VoIP phones, you should keep them connected to those RJ11 connectors. In that case, your VoIP service will not be handled by Winston in any way.

Please note that if you use VoIP over a VPN, it may be necessary to whitelist your VPN's domain if it uses port 443.