Softphones are basically software apps installed onto your computer or mobile device so they can be used like a hard phone. In essence, they are virtual phones that are not tied to any physical location. You can connect a USB phone to your computer so you can leverage the softphone’s functionality and features and communicate as you would using a regular phone. Often, softphones running on a computer and coupled with a headset deliver better call quality than VoIP apps on smartphones. But generally, aside from the computer or mobile device, there is no need for other devices or physical phones that require a power adapter or an ac adapter.