杏吧原创

鈥淐ALL ANYWHERE. Talk for ever. Never pay long distance,鈥� claims the blurb from one Internet phone company. 鈥淐all anywhere the Internet goes for no more than you are already paying for your Internet connection,鈥� says a rival. 鈥淯se your PC just like a phone.鈥�

The principle is simple. Most people who use the Internet are connected via a local service provider, and pay only local phone call charges. Once connected to the Net, data is carried free of charge anywhere in the world; whether that data is text, graphics, video or voice doesn鈥檛 matter. So if you and the person you want to talk to can both log onto the Net, and both have an Internet phone, you need never again pay more than local rates for long-distance calls.

In practice things are a bit different, of course. The Internet is still a minority pastime, and talking on the Net is little more than a fad. But if the history of consumer electronics is any guide, things could change fast. Just a decade ago only dedicated hobbyists had a computer at home. Now home PCs are commonplace. The popular appeal of the Internet is also growing. Apple recently struck a deal with a Japanese game and toy company to sell a low cost box, containing a stripped-down Macintosh, that will allow computer illiterates to send e-mail and surf the Net. An equally simple black box could connect an ordinary telephone to the phone line, working as a dedicated Internet terminal that dials international calls at local rates. How long before something like this appears in your local phone shop?

The telecommunications industry is not yet sure what to make of this idea. If it catches on, a large slice of their revenue could vanish, so they are taking it seriously. But should they rubbish this new trend, or embrace it? It is a problem for governments, too. 鈥淭echnology has overtaken the regulations,鈥� says a spokesman for Britain鈥檚 Department of Trade and Industry. The DTI has already set a group of experts the task of working out how to stop cut-price Internet calls upsetting the delicately balanced tariff system that shares out the cost of international calls between countries. 鈥淔rankly it鈥檚 all a bit of a mess,鈥� admits Oftel, the government鈥檚 telecommunications industry watchdog. 鈥淪omeone has got to address the issue with legislation.鈥�

Technically, Internet phoning is a far cry from the simple electronic mail that used to make up most of the traffic on the Net. Replacing typed messages with spoken words brings a host of problems, starting with the sheer bulk of voice data compared with text. Ten years ago the modems that connected PCs to telephone lines processed only 300 bits a second. Modern modems are about a hundred times faster. But this is still only half the 64 000 bits per second that commercial telephone networks use to carry speech.

To squeeze the data through, Internet phone packages employ data compression systems that cut the number of bits per second to the minimum. Similar techniques are used for Internet radio (鈥淒on鈥檛 touch that dial鈥�, New 杏吧原创, 17 February). But while sound broadcasting is a one-way system, the Internet phone has to handle two-way traffic, which makes heavier demands on the compression scheme. The companies currently experimenting with Internet phones have their own brands of compression, but they work along similar lines. Speech is split into several narrow frequency bands, and the energy of each band is constantly monitored. The signal sent over the Net corresponds to the changing pattern of sound energy in each band. When there is silence in a particular band 鈥� or total silence as the speaker pauses 鈥� no bits are sent. Using this system, the data rate can be cut to around 10 000 bits per second.

For a modem that works at 14 400 bits per second, only one side of the conversation is sent at a time. The phone system senses interruptions and switches direction, so there is no need to say 鈥渙ver to you鈥�. With modems operating at 28 800 bits per second, the two sides of a conversation can be processed separately and carried simultaneously over the phone line at different frequencies.

When Harry calls Sally

But even with clever compression systems and good connections, Internet phones still have disadvantages when compared to traditional telephones. One of the fundamental principles of the Net is that it splits messages into 鈥減ackets鈥�, which it delivers by whatever route is best. The optimum route can change from moment to moment, so different parts of the same message may well travel to their destination by slightly different routes, and be subject to different delays. So packets may arrive out of sequence. To get round this problem, Internet phones include a memory buffer that stores packets for about half a second. This is long enough for the incoming packets to be assembled in the correct order before being converted into speech. The delay is noticeable, however, and makes talking over an Internet phone a bit like making a round-the-world call via a satellite link.

Audio quality also suffers. Though the speed is intelligible, the compression system makes it sound muffled and slightly burbly, as if it was bubbling through water somewhere along the line. It鈥檚 like 鈥渢alking on a bad international line twenty years ago鈥�, says Keith Day of British Telecom鈥檚 International Telephony Group.

To set up an Internet phone link you will need special software, and a microphone and speakers that plug into a sound card 鈥� plus a computer, of course, a modem and an account with an Internet service provider. The sound card provides the hardware that converts analogue speech into digital code and vice versa. If you have a multimedia machine it will already have one under the bonnet. Otherwise, it will cost around 拢50 to buy.

So, suppose two people 鈥� let鈥檚 call them Harry and Sally 鈥� have acquired the necessary kit and want to talk on the Internet. First they have to agree -by e-mail, say 鈥� to connect to the Internet at the same time. At the appointed hour, they both log on to their local service provider and call up a special page on the World Wide Web. Once Sally has the page in view, she sends a calling message to the computer, or 鈥渟erver鈥�, controlling the Web page. This alerts Harry with a loudspeaker ping or on-screen message. When Harry responds with a mouse click, the server puts the pair in touch. It鈥檚 like going back to the days of old-style operator-controlled telephone exchanges, only now the server does the job.

There are already variations on this theme. One is a kind of voice conference 鈥� the spoken equivalent of the 鈥渃hat鈥� facilities that let e-mail users round the world take part in live discussions online. The Californian software company Quarterdeck recently received a message of thanks from 16 ministers of religion who use WebTalk, Quarterdeck鈥檚 Internet phone program, on their personal computers to conduct regular telephone conferences.

Another kind of service is being developed by Quarterdeck鈥檚 main competitor, VocalTec () of New Jersey, working with a nonprofit-making organisation called Free World Dialup (). This will allow either Harry or Sally -though not both 鈥� to use an ordinary telephone to talk over the Net. If Sally is in London with her computer, she logs on to the local service provider and connects to an Internet phone server. It doesn鈥檛 matter where the phone server is; let鈥檚 say it is in New York. Once connected to the server, she keys in Harry鈥檚 phone number in a far-off city such as Los Angeles. The server sets up the connection from Sally鈥檚 service provider in London to a computer in Los Angeles that is fitted with equipment that can dial out on an ordinary phone line to the number that Sally keyed in.

When Harry answers the call, the computer converts his speech into a bit stream that it sends over the Net, and converts Sally鈥檚 digitised speech coming in over the Net into an analogue signal suitable for the phone line. The local 鈥渂reak-out鈥� call is paid for 鈥� at the moment 鈥� by whoever operates the local computer. More than 200 service providers round the globe are already committed to underwriting these calls, says Alex Balfour, who is working for the British service provider Global Internet on setting up such a system in London. But it is unlikely that break-outs will stay free for ever: extra service charges are almost certain to creep in to cover the cost.

There are still a number of snags. So far there are no agreed standards for Internet phones, which means that Sally and Harry can only stay in touch if they use the same company鈥檚 system. At the moment, all the companies experimenting with Internet phones are pushing their own software as the one that should become the standard. To build support for their software, some Internet phone companies are allowing people to download it free of charge (). It is a strategy that worked for the Netscape Web browser. Early versions were free, and within months it had been downloaded by people around the world. Today most users have to pay for it. For Internet phone software there is still everything to play for, but the die may well be cast by the end of this year.

Today鈥檚 successful, if limited, trials of Internet phones have left telephone companies with a problem. A spokesperson for AT&T, the American telecoms giant, began by rubbishing Internet phones before adding thoughtfully that it could be 鈥渆ither a threat or an opportunity, depending on how we respond鈥�. Tom Evslin, vice-president of AT&T鈥檚 data services, can already see a possible opportunity. 鈥淭he first significant use will be in combined voice-data application,鈥� he says. Accordingly, AT&T is evaluating Internet phone technology for use with computer helplines that will remotely diagnose faults on a caller鈥檚 computer, while the caller talks to an engineer. Evslin openly admits that Internet phone technology could 鈥渞educe the price of traditional telephony鈥�. But Day at BT does not yet see it being widely applied. 鈥淪o far it is just a niche, for hobbyists,鈥� he says.

Gloomy view

Day also points to a deeper problem, that no amount of improvement to the software is going to solve. 鈥淚f use explodes, network congestion will get worse,鈥� he predicts. 鈥淭he Internet backbone needs investment. Someone has to pay. So costs will go up. At the same time the cost of using an ordinary telephone is going down. We could see convergence.鈥�

There is no doubt that congestion on the Net could become a serious obstacle for Internet phones. Anyone who surfs the Net knows what happens when the traffic gets heavy. It slows right down, and connections can even appear to go dead. This is no more than an annoying inconvenience when reading text or downloading pictures, but for real-time conversations it is a killer.

Quarterdeck鈥檚 chief technology officer, Robert Kutnick, accepts that a potential problem exists, and offers a radical view of the future. 鈥淭he Internet service providers will do as the telephone companies do and prioritise connections so that once a call is set up the quality is guaranteed. But of course the price will go up,鈥� he says. 鈥淪o there will be a two-tier Internet, with low-cost connections for private users who are more concerned about cost than quality, and higher-cost connections for business users who care more about quality than cost.鈥� Day has an even gloomier view of the future. 鈥淎 lot of today鈥檚 Internet connections are altruistic, provided by academic networks. They were never intended for speech data which puts a very heavy load on the network,鈥� he says. 鈥淚f telephone traffic on the Internet explodes, it will push out the intended users. We could then see the academic networks struggling for survival.鈥�

When we will arrive at either 鈥� or both 鈥� of these possible futures will depend largely on how popular Internet phones turn out to be. The Internet phone companies are cagey about exactly how many people are using their software, although VocalTec talks in terms of a million users. A strong indication that the idea is catching on is the growing interest from conventional phone companies. 鈥淭he telephone companies are already working on it,鈥� says Kutnik. 鈥淚f they cannot stop something, they will make money out of it.鈥�