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Текст №1
WHAT IS VOIP?
1. Voice Over Internet Protocol (VoIP) is a new technology that uses broadband Internet and network lines to transmit real-time voice information. This technology has the potential for completely changing the way phone calls are made and making phone companies a thing of the past.
2. To make a phone call on the Internet, several things must happen. On the sending side, analog voice signals are digitized, compressed, divided into packets and transmitted over network lines. On the receiving end, the signals are recombined, uncompressed and converted back into audio. Because the voice signals are digital, they can be transmitted just like any other data packets on a network. VoIP can be relatively inexpensive to implement, although costs rise as the complexity of the system increases.
3. There are currently several problems with this technology. If the computer or network lines fail, then telephone service is interrupted. Though the stability of computer hardware, operating systems and network infrastructure has improved significantly in the last decade, crashes still occur. The "up" time of these systems is still significantly less than with traditional phone systems - which often continue to function even during power outages. Another issue is that tracking the origin of a call is difficult because the signals are transmitted over the Internet. This is especially important to emergency responders to 911 calls. Caller ID service may not function either.
4. Additionally, devices that make calls using phone lines, such as fax machines, cable TV boxes, etc. may not function properly. Law enforcement officials may have difficulty wiretapping phone lines that use VoIP technology. Finally, the quality of VoIP service is lower than that of a traditional phone system. Since the information is transmitted over network lines, VoIP phone calls may break up, hesitate, or cause words to be dropped. All of these issues are being addressed and their significance should be eliminated over time.
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Текст №2
In the 1960s, researchers began experimenting with linking computers. They wanted to see if computers in different locations could be linked using a new technology known as packet switching. This technology, in which data meant for another location is broken up into little pieces, each with it’s own “forwarding address” had the promise of letting several users share just one communications line. Their goal was not the creation of today’s international computer-using community, but the development of data network that could survive a nuclear attack.
Previous computer networking efforts had required a line between each computer on the network, sort of like a one-track train route. The packet system allowed to create data highway. Each packet was given the computer equivalent of a map and a time stamp, so that it could be sent to the right destination, where it would then be reassembled into a message the computer or a human could use. This system allowed computers to share data and researchers to exchange electronic mail, e-mail. In itself, e-mail was something of a revolution, offering the ability to send detailed letters at the speed of a phone call.
As this system grew, some college students developed a way to use it to conduct online conferences. These started as science-oriented discussions, but they soon branched out into virtually every other field, as people recognized the power of being able to” talk “to hundreds or even thousands of people around the country.
In the 1980s, this network of networks, which became known as the Internet, expanded at a phenomenal rate. Hundreds, then thousands of colleges, research companies and government agencies began to connect their computers to this worldwide Net. Some companies unwilling to pay the high costs of the Internet access learned how to link their own systems to Internet, even if “only” for e-mail and conferences. Some of these systems began offering access to the public. Now anybody with a computer and modem, persistence and a small amount of money could tap into the world.