RIM Based  Networks

RIM (Remote Integrated Multiplexer) units were a cheap way for Telstra to provide a large number of phone lines over one fibre-optic cable.

RIM Based Network
RIM Based Network

The fibre-optic cable runs from the exchange to the RIM, where it is split off into many individual copper phone lines. Unfortunately RIMs prevented ADSL from being installed, because the ADSL equipment must be attached directly to the subscriber’s copper line.

Since 2003 Telstra installed CMUX (Customer Multiplexer) technology in RIM cabinets or in CMUX cabinets. A  mini-CMUX  handles the data connection back to the main exchange over the fibre optic line and provides ADSL communication.

A cmux cabinet
A cmux cabinet

RIM systems were  installed in most new Australian suburbs since the privatisation of Telstra. Although CMUXs allows ADSL,  suburbs with these systems typically have much slower ADSL than that provided by the old CAN.  Many people moving from an older suburb to a new one found to their dismay that they would have a vastly inferior internet than before.In addition, the CMUX based systems restored Telstra’s monopoly because ISPs cannot install their DSLAMs in the RIM or CMUX cabinets and were therefor only able to provide ADSL,  rather than the ADSL2+ systems possible from their DLSAMs in exchanges.  Customers on a RIM base system could only get ADSL from other vendors.  Telstra could provide a limited form of ADSL2  from their RIMS, thus forcing customers to either use ADSL or get ADSL2 from Telstra.

In the last few years the RIM situation has changed somewhat, but it still leaves third parties at a disadvantage.

This writer had the misfortune to  be on a RIM for 7 years prior to May 2013.  I then had the fortune to be connected to the NBN, choosing a 50/20 iiNet plan. Below are my before and after experiences:

Before:  speedtest rimThe was on a ADSL1 plan (All that was available), costing me on average $103 per month, including phone. The connection was unstable and the speeds became worse during evenings.  My connection was lost about two or three times a year, requiring Telstra to send out a technician. It took about 2 to 3 days per incident for the connection to be restored.


speedtest NBN

This on a 50/20 iiNet plan, costing me $85 per month, including VOIP. All local and national calls are free.  I have not lost my connection once since NBN was activated 6 months ago. Download and upload speeds never vary.