Cable modems use the Hybrid Fibre Coaxial networks laid by cable TV providers to transfer data at broadband rates. Although a cable modem modulates and demodulates between the analog cable medium and your PC's digital signals, it is a far more complex technology than a telephone modem.
A cable modem has two connections, one to the cable wall outlet and the other to your PC. The cable modem can be either an external or internal device with the former connecting to your PC with either the USB port or 10BaseT Ethernet. And, like ADSL, the cable modem is permanently connected to the network.
It's common knowledge that the speed of your cable modem depends largely on how many subscribers on your street (or in your node of the network) are currently online, as you all share a chunk of bandwidth. So, the more users online, the smaller your chunklet will be.
However, it is a misconception that the cable TV subscribers on your street also steal your cable modem's bandwidth: the different services within the physical cable are frequency divided. Your cable modem's upstream and downstream channels each have a dedicated frequency band that is completely different from the frequency bands allocated to cable TV.
Vendor-quoted cable speeds range from 256Kbps to 2Mbps downstream and 64Kbps to 128Kbps upstream--obviously the reality depends on the time of day you use the service and the load or number of subscribers connected at the time.
Some vendors, such as Optus, are hesitant to give firm download speeds but from other sources we are under the impression that it is in the region of 2Mbps. It is interesting to note that the DOCSIS standard--currently used on Optus' and Telstra's networks--allows for maximum cable speeds up to 10Mbps.












I was sure you couldn't get T1 and T3 services in Australia, that it's a US standard, instead we have 2Mb links instead of their 1.54 ?