Meaning "sound over distance," it refers to electronically transmitting the human voice. In the beginning, telephony dealt only with analog signals in the circuit-switched networks of the telephone companies. It later referred to a mix of analog and digital circuits, but still with the telephone industry. Starting in the 1990s, telephony began to embrace sending voice over IP (VoIP) networks, which is now deployed by common carriers, private enterprises and independent VoIP providers (see VoIP and IP telephony).