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How do I / My Telco identify the main port?

Discussion in 'Networking' started by Zapmaster14, Aug 11, 2017.

  1. Zapmaster14

    Zapmaster14 Site Founder Staff Member

    I had a bit of a funny story apparantly there is a second telephone port in my home, I didnt realise as I am renting and it had always been blocked by furniture!

    Anyways it seems that this second port is closer to the conduit leadin (Grey telstra box outside the house) I know for newer houses this is where the copper is run into the house.

    Is it usually by design the closest port to the leadin is the "main" port?

  2. cefiar

    cefiar Premium Member Premium

    The only way to be sure is to trace the wiring. This could be done a number of ways but usually the easiest is to simply open up the cover of the connectors and look.

    Phone sockets usually get run in parallel (lets not get into alarms and the Mode 3 sockets here, that's its own can of worms), and the easiest way to do this tends to be to simply run other sockets off the connections in the first or primary socket. If it's one of the old 610 series sockets (not the Modular RJ12 ones), then you only need to remove first screw and look under the cover. Only pins 2 and 6 tend to matter on the 610 series sockets, though depending on how things are hooked up, you might find more pins are used.

    If you see that each terminal has 2 (or more) wires going to each screw terminal, then one of those will be coming from the outside and the second (or more) will be going to another socket. Same applies to the modular sockets, though how the sires connect to them varies depending on the socket design.

    Now, connecting to the "main" or primary socket gives you the shortest cable length, but it can actually introduce issues due to the remaining "stub" of phone cable to the second socket. This is a real problem when you have long chains of sockets or a star setup (where more than one socket is run from the primary socket, direct to each socket). Basically each pair adds some residual capacitance, which can cause some of the signal to reflect back to the primary socket. If it's a short single run it won't be much, but the more sockets (particularly if they all run off the primary one), the worse it will be. Also the higher the frequency, the less capacitance is needed to make it an issue (eg: FTTN & ADSL).

    If you want the shortest cable with the least problems, you're best off using the primary socket and getting all the subsequent sockets from the phone line disconnected.

    The following pages might prove useful:

    Note: Removing the cover of a 610 socket doesn't require that you have any sort of certification, as it's the only way to connect/remove a phone that has been anchored to the socket. There is an anchoring screw under the socket, so the connectors do not pull apart.
  3. Zapmaster14

    Zapmaster14 Site Founder Staff Member


    Telstra is being a pain in the ass deciding wether or not they will charge $130 for an incorrect callout charge, claiming that maybe the equipment is plugged in pass the "Network Boundry Point"

    Ah, Bloody Telstra.
  4. cefiar

    cefiar Premium Member Premium

    The other way to do it is to use a line length tester (which requires disconnecting the cable at the Telstra box, and therefore definitely requires a certified tech). You can then plug the "cable" you want to test into the device (there's a local and remote end) and it measures how long the cable is. Any cable you're testing needs to be completely disconnected from anything else, otherwise you'll kill the test device.

    These are usually made for network cables, but they'll work on phone pairs too, especially if you use a little adaptor to map the pairs onto the right wires. They're usually only good for lengths over 5m though, as shorter than that is hard to get right without expensive electronics.

    I bought one on eBay for about $30. I use it for work testing network cables and network runs, as it'll show you when a pair is broken and in some cases can tell you how far away the break is (eg: bad termination at one end or it's broken in the middle somewhere).
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