Voice Over IP is the process of transmitting voice communications, like phone conversations, over an IP based network like the Internet. It uses IP addresses instead of phone numbers, and Ethernet cable in place of phone wire. VoIP can performed by an application like Skype, or a device like an IP phone.

The major difference between IP based voice communication and the telephone network we are all accustomed to using is the method of sending data. Both methods convert sound to electrical signals (data) and send it over a network to the recipient, where it is converted back. The networks they are sending data over are vastly different, however.

A Public Switched Telephone Network (PSTN), our standard phone system, forms a circuit between the caller and the callee which stays connected for the duration of the call. IP calling uses the Internet, a packet-based network. This means that data is transferred in discrete packets which are sent from source to destination independently and assembled when they get there. This is more efficient and much less subject to distance issues than a PSTN. This is half the reason why VoIP calls are so much cheaper than PSTN calls. The other half is the fact that the Internet is more or less globally maintained, whereas phone systems are implemented and maintained by individual governments and corporations. So while you and your phone company need to pay for the right to use a remote phone system to connect, there is no such need on the Internet. Once you are on it, you can send data without restriction or cost.

VoIP programs like Skype have the run of the Internet, and no one is trying to charge long distance rates for that (at least not yet), but there’s a bit of a snag when it comes to regular phones. See, regular phones are connected to regular phone lines which are administered by regular phone companies who would like regular payment for their services, thank you very much.

Understandably, the company you pay for your telephone access is not overly keen on the idea of you being able to dial up anyone, anywhere in the world, for free. They don’t have much to worry about though… In order to bridge a call started on the Internet (via a VoIP application or phone) through to PSTN (Public Switched Telephone Network) phone, a special connection device is needed to bridge the gap between the packet-based Internet and the circuit-based telephone network.

The VoIP Gateway is a device that connects and translates the Internet and a regulation phone line. A user makes a local phone call or a VoIP call to the gateway, which then transfers the call over the Internet to a second gateway which dumps it back onto the regular phone system at that location.

In this way, long distance charges can be circumvented, and regular phones used to call computer systems and vice versa. However, while these VoIP Gateways are available, they are not yet at a cost or a simplicity that would make them desirable for home users. Also, in order to use them effectively, you need a gateway at every location you intend to call regular phones at. This is expensive and complicated, which explains why full global VoIP calling is still the domain of major corporations and institutions that can afford the initial expenditure required to set up a VoIP network.

VoIP is becoming more common internally, within large institutions like college campuses. There it provides an effective means of communicating within the campus grounds, requiring only an interface to the regular telephone system to ensure that any calls out are transferred to that network.

To sum up, things get complicated when you start thinking about calling from your computer to someone else’s phone. As long as you keep things strictly Internet-based though, there’s no extra cost incurred, paving the way for services like Skype.

Source

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This entry was posted on Sunday, November 28th, 2004 at 5:05 pm and is filed under News. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.