Tuesday, July 27, 2004
RIM Exchanges
What is RIM and why does it prevent the use of ADSL to some home orbusiness locations?ADSL only works when there is an un-broken copper path between yourpremises and the DSL 'head-end' device (called a DSLAM). This meansit needs a clear copper path between the telephone exchange and endusers house. When your connected to RIM it means this does not happenas the RIM is connected back to the main exchange via optical fibrecabling.
A RIM (Remote Integrated Multiplexer) is a device (often a 'streetpillar') which sits at the edge of a suburb or an industrialdevelopment area. It is installed by Telstra when there are not enoughcopper lines available between a telephone exchange and a set ofcustomers. What a RIM uses is an optical fibre cable from the exchangeto the site of the RIM. Leaving the RIM are the necessary copper phonelines, which then connect to each home or office. Basically the mainexchange routes all telephone call data from a range of numbers downthe Fibre Cable to the RIM.
The RIM then handles the basic functionslike collecting DTMF data and reporting it back to main exchange socalls can be routed on the network. A RIM however does not routecalls locally with in its switching, rather it sends it back to themain exchange and then if the call is for a house connected to the RIMit routes the call back to the RIM exchange.
A RIM connected phone line works just like any other phone line formaking and receiving telephone calls. It just so happens that theirpresence makes the use of ADSL impossible (and they also adverselyaffect the maximum possible speed on analog dialup modems) which meansthey are unable
Telstra have the technical capability to install 'miniature DSLAM'units into the RIM boxes in the street. Doing so would 'ADSL enable'some of the customers on that rim. Unfortunately, the current technology which is an AM35 card only allows around 90 – 100 customers on a rim that can support around 400 customers.
One some types of RIM exchanges can not support a minimux or an AM35 card, which means these areas cannot get broadband services via ADSL. However, it can be possible to achieve and ADSL connection if there is an available copper connection to transpose your service onto linking it back to the main exchange rather than sending it through the RIM exchange block. However, there is only a small amount of copper lines sent out as a back up system to the RIM block. These are usually provided to emergency services or essential service personnel and premises before standard residential people. But transposing a service does not add extra space on the rim because it means someone else will miss out and have to use the RIM service.
