Yes and No. You can benefit from PSTN by pass if you are making calls to locations that are on your VoIP network or connect to other VoIP networks through an intermediary gateway. However, a large percentage of phone users will not be on VoIP. When place calls to individuals or businesses that are not on a VoIP network, your calls must be routed through the PSTN. Your VoIP carrier will seamlessly and transparently coordinate this.