Upgrading a 600-series phone socket to RJ11

Live in Australia and have an old, crusty phone socket that needs to be upgraded?  Not sure if you can DIY or whether you should call a sparky?  If so, read on.

Telecom/Telstra has installed millions of 600-series phone sockets in houses all across Australia since the 1960s.  If you have one, it probably looks something like this:

If you’ve bought a phone recently, however, the chances are it no longer has a 600-series plug.  It probably has an RJ11, RJ12 or RJ45 plug instead — something like this:

So, what you probably want to do is upgrade your old phone socket to one that will suit your new phone’s plug — something like this:

Whilst there are a lot of possible combinations of old sockets, wires and new socket options, I’m going to explain the simplest case so that you can grasp the bare essentials of what is involved.  If you are still confused at the end, keep researching or call an electrician.

If you remove the cover plate of the old (600-series) phone socket, you will see six screw terminals attached to six connectors arranged in pairs.

Each screw/connector should be numbered (from 1–6) but, if they aren’t, just start your numbering from the outermost connector in the group of four.  Thus you should have 1&2 then 3&4 then a gap (to receive the non-conducting spigot) followed by 5&6.

In the simplest case, you will only have two wires connected to screw terminals.  A white and blue striped wire should be connected to terminal 2, and a blue wire should be connected to terminal 6.  By convention, the white and blue striped wire is referred to as the “white” wire — thus white connects to terminal 2 and blue connects to terminal 6.

For a single, regular, no-frills phone line that’s all you need — one pair of copper wires.

NB:  These wires usually have ~50V DC open circuit which jumps to ~100V AC when a call comes in.  Shorting or earthing them can give you a nasty zap or damage expensive equipment at the exchange which can easily be traced back to you.  If you aren’t competent to handle such live wires without causing damage, don’t proceed — call an electrician instead.

Remove the mounting screws holding the socket’s mounting-plate to the wall.  Carefully pull the plate out so you can check the back for any surprises.

Using an insulated screwdriver, release the white wire from terminal 2.  Snip the exposed/stripped section of wire off with insulated cutters to minimise the chance of an accidental shock or short.  Carefully withdraw it from the socket.  Bend the wire out of the way and tape it for extra safety if you wish.

Using an insulated screwdriver, release the blue wire from terminal 6.  Snip the exposed/stripped section of wire off with insulated cutters to minimise the chance of an accidental shock or short.  Carefully withdraw it from the socket.  Bend the wire out of the way and tape it for extra safety if you wish.

Dispose of the 600-series socket and mountingplate.  Keep the mounting screws.

Now let’s turn our attention to the replacement socket.

The simplest Registered Jack (RJ) that will support a single phone line (pair of wires) is the RJ11.  The RJ11 has 6 Positions where wires can be inserted and connected to pins, but only 2 Contacts have actually been made — thus RJ11 is also known as a 6P2C connector.

NB:  Your phone may have an RJ12 plug.  This is exactly the same size and shape as the RJ11 but instead of only 2 Contacts it may have 4 Contacts — thus RJ12 is also known as a 6P4C connector.

All you need for a basic phone service (which fully supports ADSL in both its normal and naked forms) are two copper wires, so a 6P2C RJ11 socket is all you need.  If you can, get one.  But since it costs a negligible amount more for manufacturers to make 6P4C RJ12 sockets (which get used a lot by companies) it will probably be easier to find and use one of those instead.  Something like this would work just fine:

RJ12 IDC Socket

(“IDC RJ12 Telephone Wall Plate Socket” from Jaycar Electronics)

The back of the socket will have colour-coded slots for wires.  You run each wire through the channel in the middle, then through the same-coloured slot.

NB:  You should easily find the blue slot, but you will not find a plain white slot.  Look for a white-blue slot (often a rectangle or square split diagonally with white in one half and blue in the other) — the white and blue striped wire goes in the white-blue slot.

In each slot are two small conducting blades.  If you push the wire down to the bottom of the slot, the blades will cut through the sides of the sheath and make contact with the bare metal inside.  To help you with this process you may want to get yourself a punch down tool — something like this:

Punchdown tool

A punch-down tool is not required — you can easily accomplish the task with one or two thin screwdrivers, a pair of scissors/clippers, and by exercising a bit of care and patience. However, given that punch-down tools can be found for ridiculously low prices on eBay (e.g. $1.61 from Hong Kong with free international shipping) why not buy the tool and make your life easier?  Especially if you have more than one socket to replace, or know other people that have sockets that could do with replacing down the track?

Using a punch down tool (or otherwise) punch the white(-blue) and blue wires down into the correct positions on the RJ11/12 socket:

Punchdown in action

The above image shows not only the white(-blue) and blue wires being punched down, but others as well.  Orange and white-orange are the second pair that enable RJ12’s extra functionality.  For RJ11 you do not need to punch down anything but white(-blue) and blue.

Once you have punched down the white(-blue) and blue wires it should look something like this (but with the loose ends trimmed off):

Punchdown complete

Two wires punched down into their corresponding slots on the back of a RJ11/12 socket with all of the other wires folded out of the way (not punched into the socket).

Secure the unused wires with electrical tape, cap the back of the socket (if it has a cap) and then plug your phone into the socket and test to make sure it works.

If everything is working then push the socket into its mounting-plate and mount it on the wall using the original screws that you saved.

Tidy up and you’re done.

PS:  Assuming that you buy a RJ11/12 socket, mounting plate and punch down tool, you’re still going to have change left over from $30 and should be able to complete the above process in less than half-an-hour.  Each additional socket would cost you less than $20 (since you now have a punch down tool you would only need to buy the socket and plate) and would only take about 10 minutes to upgrade.  A sparky would charge around $80 per socket.


113 thoughts on “Upgrading a 600-series phone socket to RJ11

  1. Hi Chris,

    The blue/white pair — in the lead-in cable that comes from the box on the outer wall of your house — is, in your case, the only ‘active’ line. The red/black pair is not active, which means the other end of those wires are not connected to anything back at the exchange. The red/black pair is completely independent from the blue/white pair. They have nothing to do with each other. Connecting the red/black pair to your main outlet (or any other outlet) will not accomplish anything. It will not make your Internet go faster.

    Back in the ’80s that second line (the red/black pair) was often used for a fax machine, or a second voice line for the kids, or a business line for a home office. In the ’90s and early ’00s when we were using analogue modems (56kbps and slower) you couldn’t be online and make voice calls at the same time, so people used the red/black pair for Internet access, while retaining the original blue/white pair for voice calls.

    Then along came ADSL, with signalling that could be layered on top of a regular phone line (thanks to inline filter/splitters), so you could have both voice and ADSL on the same line. The red/black pair fell (back) into disuse when that happened.

    With the rise of mobile telephony, an ever-increasing fraction of homes don’t have PSTN (old-school “land-lines” that just carry voice calls) at all. They either use a single copper pair, or fibre-optics, to deliver a digital signal to the home. Voice calls, if any, are handled by DECT/VoIP handsets — making voice just another type of data that needs to be transmitted, little-different to web pages, images or audio/video streams.

    Your comment does not make your telephony situation/requirements clear. Nonetheless…

    IF you have 2+ old-school analogue phones, and an old-school land-line (i.e. have a dial tone when you pick up a handset), and want to keep those ‘vintage’ items working in different rooms, all sharing the existing, single phone number, then all you need is for the blue/white pair to be connected from your main outlet to all of the others. When someone calls your phone number, all of the phones connected to all of the outlets will ring. If one phone is being used to make a call, and someone picks up a handset in a different room, then they can listen in on (or participate in) the established call. That is “normal” but may or may not be what you want.

    IF you want a second, independent, old-school land-line, so that you can conduct two independent and private analogue voice calls at the same time (or use fax machines, older security devices, or medical alert systems), then you need to ask Telstra to activate your second line (the red/black pair). This is the ONLY situation where red/black wires matter. If you want to have a second land-line then, obviously, you need to make sure that the red/black pair is connected to the outlet(s) that need to use it. (Be advised that unless you have exceptional circumstances, Telstra will likely refuse your application. The PSTN is being decommissioned in favour of the NBN, so new connections are rarely allowed.)

    IF you have ADSL/NBN, then there is probably no need to have an old-school voice line at all. Just add a VoIP phone number to a Naked ADSL plan, or a NBN plan, and use digital voice instead of analogue voice. If you do that, then you do not need to worry about connecting your other two outlets at all. All data comes into the main socket, into a router that is capable of connecting to either DECT or WiFi cordless phones. You can have as many such phones as you want, they can be moved wherever you want, whenever you want. All you need is for the cradle they sit in to be close to a power outlet so they can be recharged when not in use.

    Hopefully one (or more) of the above three scenarios matches your situation/requirements. If not, let me know what you want your system to do, and I’ll try give you more useful advice.

  2. Hi Tim,

    Thanks very much for the detailed reply and explanation, it is greatly appreciated and exactly what I needed. Apologies if my original explanation didn’t quite make sense – I’ve been on night shift this week and it was making sense to me but I was struggling to put it into words!

    The last situation you describe is how we are set up – we have nbn FTTN at our address (regional Vic) so our Telstra nbn Smart Modem connects to the outlet with the blue/white pair connected. Everything else, including a home phone if we choose, runs from this modem. So essentially as you described very clearly, we only need one outlet using the blue/white wires, and the other two outlets (and red/black wires) become/are redundant.

    All makes sense now, and pretty much means I can leave it all “as-is” as it’s working fine.

    Many thanks again Tim, very much appreciated!

    Stay safe,


  3. Chris, I’m happy that post clarified things.

    One thing I will add, though: NBN FTTN uses a technology called (Vectored) VDSL between the FTTN cabinet in the street and your router. VDSL is very sensitive to interference. Telephone extensions — whether they are in use or not — increase interference (because of things like signal echoes). Reducing interference will improve the signal:noise ratio on your copper lines, reduce transmission errors, and improve transmission speeds. Disconnecting all of the other sockets from your main socket will remove them from the equation and improve your Internet speed. Many folks living in old houses have more than doubled their Internet speed by physically disconnecting the wiring leading to extensions. I don’t know how old your house is, but it’s something to keep in mind. Disconnecting unused extensions will certainly not hurt your Internet speeds.

  4. Many thanks again Tim, really appreciate it 🙂

    It’s all set up now as you describe – blue/white pair connected to the main socket only, and the other two sockets (although physically still there filling the hole in the wall!) are disconnected from the blue/white wires. It’s basically a straight run from the lead-in box to the main socket with no other connections. Internet is up and running fine, as well as the phone.

    Cheers mate! Have a great weekend.

  5. Hi tim, just scrolling through all the info that you have provided to people over the years most impressive ! l also have a question for you , ive currently got FTTN to our house and am wanting to change our internal wiring which is old cream telephone wiring from when the house was built in the 90s, i want to change it to cat6 , is there alot to do where the old line first enters the house from under the eves or can i just plug a cat6 straight in and run the cable to the wall plate that connects to my computer, hope ive explained it ok. thanks for any help. Dean.

  6. Dean, even though your Internet connection has fibre in its name, the segment from the FTTN cabinet in the street and your house is still just plain old copper and only two of these copper wires are needed. The technology you need to deal with inside your house is little different to the way it was 20 years ago. VDSL is more susceptible to interference from both used and unused extensions than ADSL, so apart from making sure your internal wiring is as minimal as possible (i.e. disconnect unused extensions), there’s not a whole lot more to say.

    There is not much to be gained changing the 4-wire cable from the box you probably have on one of your outside walls to your ‘primary’ outlet. Most of that is hidden and swapping it to Cat 6 will gain you nothing as far as performance is concerned.

    Updating the outlet to have a more modern wall-plate and socket (e.g. RJ11/12/45) is what this article is all about, so that’s already been covered.

    To update your existing cable to be functionally-compatible, the fastest/cheapest way is to just cut off the plug that normally goes into the wall, and crimp on a RJ45 plug instead (if you have a crimping tool).

    If the socket on your modem/router is already RJ45, and you update your wall socket to RJ45 as well, then you can throw away the old cable, buy a new Cat 5 or 6 cable of the length and colour that suits the room your modem/router is in, and just use that instead. Note that there is no technical advantage to having a thicker Cat 6 cable between the outlet and your modem (unless it runs near a microwave, induction cooktop, fridge compressor, or over a bunch of AC power cables).

  7. Hey Tim,
    I’ve just recently moved into an older house (maybe 1960s build) and I’m wanting to upgrade from the old style phone socket. I’ve just been to bunnings and bought an rj12 wall socket (they didn’t have any rj11) but I also picked up a cat6 socket. Anyway I’ve just taken the old socket off the wall (which wasn’t wired up) to find 2 separate lots of cabling, both have a red, black, white and blue wire. So my questions are; 1 does it matter which set I use? And 2 can I connect the cat6 port or do I just go with the rj12?
    Thank you,

  8. Jack, if the socket you are talking about is the main/primary/first socket for the house, then one of those cables is leading in from outside, while the other one is heading to an extension in some other room. To work out which is which, carefully separate the two. The cable leading out of the house will still be connected to the telephone network and will still be live. The cable connected to your extension will be dead.

    If you have an old-school landline (i.e. have a dial tone), you can use a multimeter to check the voltage between the blue and white pair of wires on each cable. You’ll see 0V DC on the dead cable and ~50V DC on the live cable. If you don’t have a dial tone (i.e. are using Naked ADSL or one of the VDSL-based NBN technologies) then it’s not so easy. Unless you want to spend $$ to $$$$ on a dedicated testing unit, the cheapest way is to just hook one cable up to your socket, connect your router, turn it on, and see if it line-syncs. If the first cable you hook up works, then that’s the live one and the other one is the dead one. If the first cable doesn’t work, then it is the dead one and the other one is the live one — so disconnect the current cable and hook up the other one. Your socket should now be connected to the live cable.

    Assuming you don’t need or care about that other extension, you should leave it disconnected and only hook up the live cable to your new socket.

    As for which socket to use, that’s easy: Use the socket that matches the appropriate port on your router. If your router has a RJ12 port, put a RJ12 socket on the wall. If your router has a RJ45 port, put a RJ45 socket on the wall. That way you can simply buy a suitable cable from a store (assuming you don’t have one already) and plug it in with no further messing around (no need to track down or create a custom cable with one type of plug on one end, and a different type of plug on the other).

  9. Hi Tim
    My phone line appears to have red, orange, white and grey wires. Can you please help me wire into an RJ45 socket? Would the grey wire be my blue and my white be my blue/white? What about the orange and red wire?

    Appreciate your help

  10. Dominic, those colours are unlikely to be present in a cable installed by a Telecom/Testra tech to the original/primary phone outlet in a house. What I suspect you are looking at is an extension that was added later. I suggest you check your other outlet(s). The cable with the colours you are currently seeing should daisy-chain back to the primary outlet. There you will be able to tell what corresponds/connects to the blue and white wires. The other two don’t matter (unless you have an active second line, as mentioned in a number of comments previously).

  11. Will a RJ11 socket work with NBN? any difference between those two for NBN? Thanks

  12. Andrew, NBN isn’t ‘one simple, consistent and universal thing’. NBN connections are delivered using several different and incompatible technologies. Some make use of the old copper telephone wires going into people’s houses, some don’t. FTTC and FTTN (for example) use VDSL to get inside your home and connect to a NBN router. VDSL and ADSL are very similar, so a pair of telephone wires that once carried ADSL is very likely to be able to carry VDSL (and hence support a FTTC/N NBN connection). In such cases, whether or not you can use the RJ11 socket on the wall primarily depends on your router. If your router also has a RJ11 WAN port then yep, it should work without any dramas.

    If, however, your router doesn’t have a RJ11 WAN port (many now have RJ45 ports) then things get complicated. If the NBN technology that connects to your house doesn’t make use of the old copper phone lines, then it gets even more complicated.

    For bureaucratic reasons, NBN Co has determined what one-and-only-one connection technology is permitted at your address — you don’t get a say. Their decision determines whether or not any existing telephone infrastructure (e.g. a RJ11 phone socket on a wall) will get re-used or not. If it won’t get re-used, the NBN technician will install new infrastructure appropriate to the technology being used. Then it’s just a matter of getting a router that is compatible with the infrastructure on your wall.

    I don’t know what “any difference between those two for NBN?” is actually asking, but I hope the above helps.

  13. Thanks Tim, I worked out the connections. I was drunk and high at the time so I didn’t know my arse from my elbow, I problem I have when I’m sober, which is rare of course.

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