With Internet telephony or VoIP, you place a voice call either from your computer to another person's computer or to a landline or mobile phone. When calling from computer-to-computer, both parties must have compatible telephony software and be online at the same time. At the moment, there are no universal standards, so be sure to determine which software the person you want to call uses. Calling from computer-to-telephone is simpler, because only you need the software. You can download telephony software and it's free. In either case, you'll also need some hardware: a sound card (most computers already have one installed), a microphone and speakers (or a headset).
Computer-to-computer calls typically require advance planning, as both parties have to be online. Once your software is configured, you enter the number of the computer you want to call, click on a Dial button and wait for someone to answer. Computer-to-phone calling works much the same way, except you are calling a regular telephone number. Sounds simple, doesn't it? So what's the catch? To answer that question, you have to understand a bit about the technology.
The transmission of two-way voice communication through over the public Internet is called Internet telephony. For various reasons, the most important of which are assurance of quality voice transmission and national security, Net telephony is not allowed in most of the countries.
A category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls. For users who have free, or fixed-price Internet access, Internet telephony software essentially provides free telephone calls anywhere in the world. To date, however, Internet telephony does not offer the same quality of telephone service as direct telephone connections.
How it Works
When you place a call over the Public Switched Telephone Network, a dedicated circuit opens between you and the person you call. The line remains open until you hang up. With VoIP, your voice is digitized, then broken into small data packets. The packets travel to their final destination over the Internet, where they are reassembled into a "voice." This is the same process used for sending e-mail. With e-mail, however, it doesn't really matter in what order or when the data packets arrive. Once they all arrive, you can read the message. Since voice communication happens in real time, if some of the data packets are delayed or lost en route, the voice quality degrades.
The quality of your call depends on the speed of your Internet connection and that of the party you call, and the traffic on the Net. If the data packets are delayed during transmission, it causes latency, a fancy word for the lag time between when you speak and when the other party hears your voice.
Although it can be annoying, you can learn to compensate for latency. A greater problem is voice distortion. When packets are lost during transmission, telephony software automatically "fills in the blanks" by examining the adjacent packets. The more the software has to compensate for lost packets, the greater the distortion.
If you are willing to accept less than perfect voice quality, Internet calls will save you a bundle of money, especially for international calls. While this may not be the optimum way to make important business calls, friends and family are usually more tolerant of odd noises on the other end of the line.
NetMeeting from Microsoft lets you make worldwide computer-to-computer calls and in some cases, computer-to-telephone calls. You may already have this program installed on your computer. If not, download it from Microsoft's website. NetMeeting also has many other excellent features for online collaboration.
Windows Messenger also include telephony features. You can download the software for free from the Microsoft website.
Internet telephony is the wave of the future, with many industry analysts predicting that all phone calls will eventually be free. As telephony standards emerge and bandwidth increases, this is becoming a distinct possibility.
Vonage has taken Internet phone calling mainstream and offers a variety of flat-rate service plans for unlimited calling.
With Skype, now owned by Internet auction giant eBay, has soared in popularity for its user-friendliness. The software works on PCs running Windows, Mac OS X, Linux and even Pocket PCs. Computer-to-computer calls are free, but it will cost you to use SkypeOut, a service that let's you call telephones.
Net2Phone offers a variety of calling plans, depending on your needs.
PC calls when you use Yahoo! Messenger, and worldwide calls for only a few cents per minute.
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