What Is VoIP Service?

by Robert Vega

VoIP stands for "Voice-over-Internet Protocol," an alternative to traditional analog telephone service that converts voice into digital signals and send the signals over the high-speed networks that connect computers to the Internet. VoIP uses communications servers and routers and makes possible the low-cost or free services offered by "Internet-only" telephone-service providers.

What Is It?

"Voice" is the transport of the electronic signal generated by a person's voice in one telephone to the called telephone. The signal goes over a link that may be a cable-company coaxial, fiber-optic from local telephone companies or wireless service from a cell company. Internet protocol is the set of rules that specifies how communications devices must format and transport digital messages.

Analog vs. Digital

When a telephone conversation is sent over a traditional wire link, the signal becomes an electronic analog for the voices and reproduces these sounds at the far end. Data communications are digital and consist of moving strings of electronic bits, generally referred to as 1s and 0s, over a means of transport. The medium may be wire, light, infrared or radio waves and the "on/off" nature of a digital signal makes it easier than an analog signal to send electronically.


The PSTN---public-switched telephone network---was designed to carry sound, specifically the human voice, over wire and for 100 years performed the service well enough that users could recognize each other even on long-distance calls, but it could not support data well. Toward the end of the 20th century, as computers got less expensive and more powerful, the benefit of connecting them encouraged the invention of networks to tie them together, including LANs---Local Area Networks---and WANs---Wide Area Networks, but they could not carry voice well. Ultimately, the challenges of carrying voice services was overcome and VoIP became a reality, first on private digital facilities and then nationally and globally.


VoIP service requires high-speed digital service, a computer, servers and routers, a structured wiring environment, a high-speed network and VoIP telephones, though VoIP systems normally offer support for analog telephones and fax machines.


VoIP offers lower cost than traditional local and long-distance service and the potential efficiency of managing a combined data and voice network. In addition, VoIP features that were previously costly add-ons such as voicemail and conversation recording, and features such as number portability, caller ID, call waiting and call forwarding, are integrated with VoIP.

Concerns: Emergency Services

VoIP services were not required to support emergency services until mandated by the FCC in 2005. Carrier-level and business-service providers developed direct access to emergency services, but Internet-only providers have gaps in their coverage and access, so their customers should verify what 911 limitations there may be for the service they use. See Resources for more information on VoIP and 911 service.

Other Concerns

Depending upon the implementation, a VoIP service may not work during a power outage, and directory assistance may not be part of the VoIP provider's offerings.

About the Author

Robert Vega has more than three decades in Telecom project and operations management. Vega's current focus is on strategic business solutions and trends in telecommunications, proposal and RFP development, and translation/localization of technical, user documentation, and voice prompt scripts into American English, Canadian French, and Latin American Spanish.

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