The broadband benefits promised by advances in asymmetric digital subscriber line (ADSL) technology may not be available to all of the world's telephone users because of political issues.
ADSL enables carriers to provide high speed communications similar to those offered by fibre cable, but over existing copper pipes. This enables users to surf the Internet and take phone calls at the same time.
But carriers need to use specialist equipment to test whether they can provide ADSL services for all of their customers because it may not be worth their while offering them if they cannot. The ADSL Forum is expected to vote on specifications for these tools during their next quarterly meeting in May.
Bill Rodey, vice chairman of the ADSL Forum said that some subscribers may not have access to the services because they are too far from the telco's central office, are served by digital loop carriers or because of the limitations of the technology.
But "these are exceptional cases and most customers can be served ADSL," he said.
A working text of the standards and specifications is already available to ADSL Forum members, but once approved, they will appear as technical references.
Carriers have been slow to offer ASDL services, particularly in Europe, although trials are currently taking place, because many observers believe that a range of political issues involving regulators and operators have slowed its uptake down.
Carriers such as BT, which own the so called local loop - the telephone line that goes directly to customers? doorsteps - are not keen to be rushed into opening their networks.
Other issues still to be thrashed in the ADSL community include the problem of modems not being able to support all operators? networks.
ADSL modems currently only work against selected carrier networks, but the forthcoming G.Lite standard, which is due to be approved by the International Telecommunications Union in June, will address this problem. Modems that support multiple carriers are expected to appear by the end of the year.
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