Voice Over Internet Protocol, oftern abreviated as VOIP, is a technology that allowes Internet users with high-speed network connections to make telephone calls to other VOIP users or landline telephone customers. VOIP was pioneered during the late 1990s, developed over several years and offered as a commercial product in the first decade of the twenty first century. Because VOIP uses the Internet as its telecommunications infrastructure, the technology eliminates the costly telephone network and allows users to make telephone calls at much less expense.
History
Many experts trace the origins of VOIP technology to a small company called Vocaltek. In 1995, the company developed and released a product called "Internet Phone" that attempted to establish voice conversations across the then-sparsely populated Internet. Although the product initially promised telephone-quality conversations, the lack of bandwidth at the time contributed to problems with latency, jitter and packet loss, all problems which interfere with the quality of voice over IP traffic.
As the Internet grew, more users came online, and bandwidth became more plentiful. Several established instant messaging services adopted the VOIP technology to allow their users the ability to supplement their text chats with voice conversations. As the technology matured and developed new protocols--including the standard Session Initiation Protocol (SIP)--it was adopted by more and more users. Large telecommunication companies took note of the potential cost reductions and began shifting some network traffic from traditional circuit-based archeticture to IP-based construction. By 1999, manufacturers of industrial-grade telecommunications equipment were offering VOIP telecom switches and other network elements.
In the early 2000s, commercial VOIP companies began offering residential and business telephone service to end-users based solely on VOIP technology. Companies such as Vonage and Packet 8 promised subscribers low monthly base prices for telephone "lines" with extremely low cost (or, in many cases, free) long distance and international calling plans. As broadband Internet service offered consumers increasing amounts of bandwidth, the offering became more practical and was widely adopted with consumers eager to cut back on expensive traditional telephone costs.
Function
Voice Over Internet Protocol (VOIP) works by modulating speech and/or sound input by a regular telephone receiver into packets of data. These packets sent from the sending router or premesis equipment out over the Internet to either a VOIP server or a VOIP gateway that serves as a bridge to the public switched telephone network (PSTN). If the dialed call (based on standard North American Numbering Plan Administration dialing patterns) is destined for another VOIP subscriber, the packets are simply directed toward the receiver's router or premesis equipment to establish the call. If the dialed call is destined for a PSTN subscriber, the VOIP gateway takes note of the dialed number, calling number and other critical call set-up information and establishes a telephone call using the traditional Signalling System Seven (SS7) call set-up process.
Features
Because VOIP uses advanced technology that is capable of quickly transferring a wealth of information, many features associated with traditional telephone service (such as Caller ID, Three-Way Calling, Call Waiting and Voicemail) are readily available to VOIP subscriber, usually for free. These features function in much the same way as the equivalent features on a traditional circuit-switched telephone system, but with all of the technology readily (and cheaply) available to the VOIP subscriber, the underlying costs are significantly reduced.
In addition to traditional telephone features, VOIP makes interesting and previously unfeasible features possible. Services such as Vonage's "Simulring" allow one telephone number to ring up to three different telephone lines at once. When one line is answered, the VOIP server recognizes the connection and immediately reroutes the conversation to that line (on a traditional circuit-switched telephone network, only one hard-wired telephone subscriber could be called at a time). In addition, VOIP users who receive voicemail can access the message directly from their phone, much like in traditional telephone service. The voicemail message may also be available, though, through an online (web) interface or even sent to the user's mobile device as a sound file.
Misconceptions
Some users consider VOIP to be experimental, unreliable or unsafe. During periods of heavy network traffic or Internet congestion, the packet-switched telephone structure may occassionally provide broken or choppy voice connections. While this effect (known as jitter) is a common and relatively harmless effect of heavy network traffic, it is not a sign of reduced reliability in the VOIP network.
Additionally, some users believe that VOIP is not compatible with E-911. Because 911 service is traditionally based on a subscriber's location (so that a 911 caller may receive the closest emergency center), many users erroneously believe that an Internet connection can not be detected by the 911 center. VOIP service providers are required, though, to maintain a physical address for each subscriber. When a subscriber calls 911, the call is matched against the service provider's database and routed to the appropriate emergency agency for the subscriber's address. Because VOIP provides all of the necessary information for a 911 system lookup, and because the address and other records are stored on the provider's servers, 911 calls across a VOIP connection function in a manner almost identical to their circuit-switched equivalents.
Warning
Although 911 service does work as designed in a VOIP setting, service providers have no control over users who choose to move their own equipment. Because a VOIP call can successfully originate from anywhere on the Internet, many users have discovered that they can "take their phone service with them" by simply unplugging the router or Internet connection at one location and plugging it in at any location (such as a hotel or relative's house) where Internet service is available. If a traveling VOIP user should need to call 911, however, the call will be matched against the service provider's records and routed to the emergency center closest to the user's registered location.
For example, if a VOIP user in Florida goes on vacation to Tennessee, he may take his VOIP service with him. By simply unplugging his router from the Internet connection in Florida and plugging it back in when he arrives in Tennessee, the user has effectively taken his telephone service (including his number) to a new destination. If this user should need to call 911, however, and has not alerted his VOIP service provider to his new location, the 911 call will coincide with the user's Florida address on the VOIP provider's servers, and the 911 call will be routed to an emergency center in Florida, hundreds of miles away from the vacationing user in Tennessee. For this reason, it is always advisable to update VOIP service records any time the VOIP equipment is moved to a new location.
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