Broadband troubleshooting: Pair Gains, RIMs and Sub-exchanges explained

  • What telcos mean when they say RIM, pair gain or sub-exchange
  • Find a broadband plan if you have an infrastructure issue
  • Other broadband connection problems explained

If you are having trouble signing up to an ADSL2+ broadband plan, you may have heard different answers from different providers. What are they talking about and what does it mean for your internet connection? Compare Broadband explains the jargon to help you find the right plan.

Pair Gain: An infrastructure problem that stops ADSL2+ from working, a pair gain system is where Telstra (when laying the copper phone lines) split the wires and shared them between two or more properties. You may still be able to get ADSL.

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RIM: A type of pair gain system allowing telephone lines to be used where the copper wire network is deteriorated or missing altogether, it is another reason you may not be able to get ADSL2+. Hopefully, you can still get ADSL, but it’s a case-by-case scenario.

Sub exchange
: Another common infrastructure issue impeding an ADSL2+ service is where a smaller phone exchange has been attached to a major exchange. You may still be able to get ADSL.

Active phone line: Some ADSL broadband companies need you to have an active line (usually on the Telstra infrastructure) before they can provide you with internet. An active line means you have a phone number and can make and receive calls on your line today.

ADSL and ADSL2+ ports: Each internet provider’s equipment has a limited number of ports in which they can offer ADSL2+ to customers. Sometimes a provider will have ADSL2+ at your local exchange, but all of its ports will be full. In this instance you can either wait, or look for a different ISP.

If Telstra’s ADSL ports are full (and it is the only provider at your exchange) you may not be able to get any ADSL service at all. Look for Mobile Wireless plans as a fallback option.

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Complex Products
: Some home phone and broadband bundle providers don’t allow specified products on their phone lines. Eftpos and FAX machines, analogue modems, back-to-base alarm systems and Foxtel Programme Purchase are all types of complex products.

If you need a fax machine on your line, try Eftel

Contention ratio: Especially with Mobile Wireless broadband, the number of users online simultaneously can slow down your connection. If a large amount of people are downloading big files or streaming data from a single DSLAM/phone exchange, ADSL connections can also be affected.

As Optus resells bandwidth on its mobile phone towers to numerous other ISPs, sometimes the network can become quite slow, especially at peak usage times (such as after work around 5:30pm).

Copper wire infrastructure: Telephone and ADSL broadband run on a copper wire network. There are two main infrastructures in Australia: Telstra and Optus. Most ISPs resell ADSL off of the Telstra network, and sometimes even Optus rents Telstra lines.

If you don’t have phone jacks in your walls or copper wire to your house, you’ll either have to get Telstra or Optus to lay them, or some ISPs like iiNet can do it as part of its service.

DID (Direct Inward Dial Number): When you set-up a brand new home phone and internet bundle you will receive a new telephone number.

DSLAM: This is the name of the equipment an ISP needs to put into a telephone exchange in order to offer an ADSL2+ service. If they don’t have their own DSLAM in an exchange they may resell off of Telstra’s equipment (but it usually costs more).
Network coverage: Each Mobile Wireless provider has certain areas where its mobile phone towers have coverage. Before signing up to a plan you’ll need to ensure the ISP’s towers cover the areas in which you would like to use the service.

Tech support: The professional technicians who can help you if there’s a problem with your broadband connection is tech support. Feel free to give them a call if an issue arises, and if having an on-shore Australian tech support team is important to you, your best bet will be to ask the ISP before signing up to its plan.
