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Other Internet Access Technologies

Some recent technological developments include:
 
Integrated Services Digital Network (ISDN)
Once promoted as an all-digital replacement for the PSTN, ISDN is widely available in Australia from Telstra Corporation (although not from other telcos). Most Telstra customers now have the option of choosing it instead of the analog PSTN. An ISDN service provides two "B channels", each of which can be used to carry either a digitised voice (or video, FAX, etc) call, or a 64 kbps data call. Its takeup has been limited by extremely high prices, and is now something of a technological curiosity...
 
ADSL
Asymmetric Digital Subscriber Line provides a high-speed (in the hundreds-of-kbps to low-Mbps range) data service over an existing phone line. The "Asymmetric" aspect is that the "downstream" data rate is usually much higher than the "upstream" rate -- an arangement which is suitable for most home users. It's also often possible to configure an "SDSL" link if preferred. This service is becoming increasingly available in Australia, and will probably dominate the market in future years.
 
Cable Modem
For areas which have an existing Hybrid Fibre-Coax (HFC) "Pay TV" infrastructure, the cable modem provides access to a shared high-speed medium (eg Optus@Home), in much the same (conceptual) way that traditional Ethernet works. Cable modems are limited by the fact that many areas do have a cable TV service.
 
Wireless Systems
A variety of systems have been proposed, none yet dominant. Watch this space...

 
Lecture 15: Point-to-Point Data Links Copyright © 2005 P.Scott, La Trobe University Bendigo.
The tutorial for this lecture is Tutorial #15.
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