Analog refers to numerous different things based on the context it is used in. An analog signal is a variable signal continuous in both time and amplitude. An analog device is a piece of equipment that measures continuous information.
Garrettâ€™s Notes on “Analog”
In the VoIP world analog is most commonly referred to when speaking about legacy telecommunications. For instance most people still have analog telephones in their home (unless they upgraded in recent years to a digital handset). An analog phone or analog telephone adaptor are two common devices that will come up in conversations dealing with VoIP, especially in a residential setting.
An analog phone plugs into on end of an analog telephone adaptor (the other “end” connects to the LAN or WAN via an RJ45 ethernet port).