Until 12 months ago ago, most modems sold supported the 28.8Kbps V.34 standard, following the standard's ratification by the International Telecoms Union (ITU).
The standard, however, took several years to be ratified. During that time the average quality of telephone lines increased, especially on British Telecom's network, thanks to its complete switch over to digital working.
As a result, several modem vendors realised that phone lines could support higher speeds if the basic compression system was souped up.
So the slightly faster speed of 33.6Kbps was born. Providing that the local telecoms connection supports a good audio link to the exchange, 33.6Kbps is easily achievable. All alternative telecom carriers such as ACC, Energis, Mercury and Worldcom have digital interconnects with BT, so line call quality in the UK has never been better.
That is why almost all modem vendors have upgraded their V.34 modems to support 33.6Kbps. Indeed, the ITU ratified the technology as the V.34x standard just a few months ago.
But if resellers have been watching the IT press these past few weeks, they could be forgiven for thinking that the modem vendor community has gone crazy, talking about modem speeds of 56Kbps as well as cable modems.
To understand how 56Kbps technology works, let's take a step back to the existing V.34/V.34x modems and the telephone networks. Today's high-speed modems use broadly the same principles as the earliest 300bps modems that appeared in the late 1970s to move data across the plain old telephone system (Pots).
Data is accepted from the PC serial port or memory bus, pumped into the modem and then converted into a signal that is modulated on to a modem carrier - in essence an analogue audio signal - for transmission across the Pots.
What is not generally known, is that the Pots is only analogue for a short distance - not even to the telephone exchange. That is because BT, in common with most telcos, uses a system known as a digital concentrator to collate calls in a given neighbourhood, digitise them, then pump them in 2Mbps channels to the actual switch.
The device at the concentrator that converts the analogue signal back into a digital one is known as a codec. Codecs are also found in digital mobile phones and they are very powerful devices.
Because most online services and Internet service providers (ISPs) are connected to their end of the network digitally, only the short distance - typically a few hundred yards - between the office and the concentrator is analogue. The rest is all digital.
The 56Kbps technology bypasses the analogue phone signal route from the office to the concentrator.
Instead of using the modem carrier to take the data from the concentrator to the modem, 56Kbps technology sends the digital packets down the copper twisted-pair cabling that links the phone subscriber to the concentrator.
The technique is similar to the one used by ISDN, except that no ISDN kit is needed at the subscriber's premises or at the telecoms switch.
The data is shuffled to the codec at the concentrator, from where it progresses as normal.
Because of the high power levels involved, only one direction of data transfer can use 56Kbps technology. The other channel, usually transmit from the user's point of view, uses conventional analogue technology to shuffle data at 28.8Kbps or 33.6Kbps.
Since most online services and Internet connections are asymmetric when it comes to data transmissions, with most of the data coming from the distant end of the link to the user, 56Kbps is ideal for transmitting data from the network to a user's PC.
By now, resellers familiar with datacoms might be wondering why 56Kbps technology does not work at 64Kbps like ISDN. Bill Pechey, technical director of Hayes' Northern European operations, explains that because only 3,600Hz of audio bandwidth is available on a local telephone loop, the available data pathway is limited to 56Kbps.
According to Pechey, if a full 4,000Hz were available, then an ISDN channel of 64Kbps would be possible.
'Since only 3,600Hz of the audio channel is available through the codec, we reckon the maximum transmission speed is about 56Kbps,' he says.
Pechey sees 56Kbps technology as best suited to Internet access, where the data is being transmitted mainly in one direction. 'For applications like videoconferencing, you'd be better off looking to ISDN for a more balanced rate,' he says.
He points out that the main advantage of 56Kbps technology over ISDN is the price. '56Kbps modem technology is much cheaper than ISDN because you don't need to have an ISDN system installed. It will work across the standard phone network using a standard phone socket,' he says.
According to Pechey, because the technology involved with 56Kbps is closer to conventional analogue modem systems than ISDN systems, adding 56Kbps transmission technology to a standard 28.8Kbps or 33.6Kbps modem will not be expensive.
'Basically you'll have a black box that will work as a normal analogue modem at 28.8Kbps or 33.6Kbps or whatever. But when accessing the Internet, providing the distant end of the link is a digital connection, you'll be able to use 56Kbps in one direction, and up to 33.6Kbps in the reverse direction,' he says.
The fact that 56Kbps technology is ideal for Internet use may explain why US Robotics has gathered support from the world's ISPs and announced in late October that all the ISPs were planning to support 56Kbps technology on their modem ports. US Robotics calls the 56Kbps technology x2, because that is the name the modem vendor has applied to its 56Kbps systems.
In fact one UK ISP, Netcom, is claiming that its network is already geared up to support 56Kbps modems. According to representatives of Netcom UK, its network has been actively testing US Robotics' 56Kbps modem technology for several months. The company claims that as a result its UK subscribers can now access the Internet at 56Kbps.
According to David Furniss, Netcom UK sales and marketing director, when he announced the opening of the company's 56Kbps modem ports in the UK, the support for x2 technology stemmed from Netcom and US Robotics' close partnership in development.
'We're pleased to be working in partnership with US Robotics and to be the first UK ISP to be able to offer our customers the ability to surf the Net at twice the current top speed, for no extra cost,' says Furniss.
'By standardising on tomorrow's technology today, Netcom is keeping several steps ahead of other ISPs.'
But it is important to realise that US Robotics' 56Kbps modems are still in alpha test and that it could be as late as the second quarter of next year before the first 56Kbps-compliant modems go on sale.
In addition, despite the enthusiasm of US Robotics European managing director Clive Hudson for x2 technology, no standards or compatibility have been agreed in the modem industry about how the technology will work.
US Robotics is something of a renegade as far as modem technology is concerned. Ever since the late 1980s when the first Courier HST modems, which worked at 12Kbps in one direction and 450bps in the other, appeared at under u1,000, the company has always taken a pioneering approach and developed its modem technology in-house.
In the late 1980s, by removing the echo cancellation and other electronic trickery from its Courier HST modem, US Robotics was able to more than halve the cost of a standard 9.6Kbps full duplex modem.
Although HST modems were proprietary, they sold like hot cakes because they were a low-cost alternative to the full duplex 9.6Kbps models. HST was later extended to work at speeds of 28.8Kbps in one direction and up to 2Kbps in the other. Again, because they were cheaper than pre-V.34 modems costing several thousand pounds five years ago, HST modems sold well, pushing US Robotics into the top sales slot in the UK retail and business channel.
Today, the company's V.34/ V.34x modems are no faster than competing products and US Robotics has lost its technical lead. But it has competed in the channel very effectively on the basis of price, support and sheer marketing muscle.
US Robotics needs the 56Kbps technology to pull ahead, in technical terms, of the modem competition in the channel. Perhaps this explains why the company has gone full tilt towards being first to market with the technology.
But there is a risk: 70 per cent of the modems sold in the channel use modem firmware from Rockwell. US Robotics, however, does not license its firmware from Rockwell, preferring instead to develop it in-house, as it has done since the earliest days.
Thus there is one group of modem vendors, including Hayes, Pace, Psion-Dacom, Shiva and others, relying on Rockwell to set the pace with its modem driver chipsets. And in the other corner is US Robotics with what will be a proprietary 56Kbps modem technology that will be first to market.
Clearly, US Robotics is betting, as it did with HST modem technology almost a decade ago, that its market presence, pricing and the immediate availability of 56Kbps will allow it to force the UK industry, including the ISPs, into adopting x2 technology.
Indeed, sources close to Rockwell are now talking about releasing its 56Kbps driver technology in the second quarter of next year and having to ensure backwards compatibility with US Robotics' proprietary technology.
Meanwhile, the ITU is considering applications for 56Kbps technology from several sources, including US Robotics, for ratification as a standard.
But according to sources close to the ITU, it could be next May, at the earliest, before the standard is finally ratified.
In fact, it could take until the fourth quarter of next year before the industry sees ratification. In the interim, it will be something of a battle of the giants - in which US Robotics is the clear favourite - to see who sells the most 56Kbps modems.
When the new standard is ratified by the ITU, the modem industry will endorse and support it. Even US Robotics will have to comply to maintain its channel presence.
But that will leave users with significant numbers of x2-compatible modems which may or may not be flash-upgradeable to the official ITU standard.
That could cause confusion among users over the next 12 months or so, and even potentially cause some grief for a reseller that recommends a corporate go with US Robotics x2 technology now, rather than wait for the ITU's ratification.
Perhaps fortunately for the channel, any 56Kbps modems will be backwards compatible with the existing 28.8Kbps and 33.6Kbps systems on most of today's modems.
The faster technology, then, has to be viewed as an interesting value-add and USP when selling modems to customers. But unless a significant portion of the online and ISP community supports the system ahead of ratification by the ITU, 56Kbps may not in the real world fulfil the promises that have been made by some sections of the industry.
Along with Netcom, Pipex has pledged its support for US Robotics' x2 technology. Pipex is enthusiastic about the technology because it means potentially increased sales of its service over the competition.
Paul Rivers, Pipex's technical director, says: 'If you said a year ago that an average user could be on the Net at 56Kbps, people would probably have accused you of being mad. But the future seems to keep arriving ahead of schedule.'
There is also the prospect of BT revamping its subscriber end of the network - the local exchange - for so-called cable modem technology. The telco's plans, which are already well in hand, are based on asymmetric digital subscriber line (ADSL) technology.
ADSL allows data to be moved at speeds of up to 7Mbps upstream and 640Kbps downstream. Thanks to the fact that the system makes use of the existing copper twisted-pair between the telephone exchange or concentrator and the subscriber premises, ADSL can leapfrog ISDN and 56Kbps technology, by several speed factors. On top of that it can be installed at minimal cost, yet offer ATM-class facilities at competitive rates.
BT intends to upgrade its network at a cost of several hundred billion pounds, mainly on the grounds that, since it is prohibited from broadcasting like the TV, cable and satellite channels, it can use an ADSL link to 'narrowcast' to individual subscribers.
Because of this, coupled with the prospect of on-demand videoconferencing, very high speed access to the Internet and online services, and support for multiple telephone conversations over a single ADSL modem costing about u400, the writing appears to be on the wall for ISDN and even 56Kbps modem technology.
Against this backdrop, by the time the ITU finally ratifies 56Kbps modem technology, ADSL may be arriving on to the market in significant quantities.
Given a choice between data rates of 7Mbps and 56Kbps, there are no prizes for guessing which technology corporate and business customers will adopt.
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