Is it possible to connect an old RJ11 phone line into a Cat 6 wall socket to use for FTTN service?

I just moved into an older house and the NBN guy told me the phone socket's been cut off and plastered over. I checked with the previous owner and he said that the cord is just cut off, sitting under the house.

I have a Cat 6 wall socket, and my question is:

Is it possible to connect the old RJ11 phone cable to the Cat 6 wall socket?

I want to use a Cat 6 plug just because there's no hardware stores nearby that sell the other ones. I intend to plug my FTTN (fiber to the node) modem into it.

No. Both technically and politically.

The technical problem is that the "NBN guy" visited your premises to install a new cable between the node and your house and to install a new socket inside your house. This is usually done by tying the new cable onto the old cable in the street, then pulling the old cable out from the wall socket until the new cable appears inside the house. With the old cable cut at an unknown location it cannot be used to pull the new cable.

The political problem is that you do not have a first socket. It sounds as though it was removed illegally, or you would have been in the Telstra database as having no existing connection. Now that the installer has completed a job report on the unsuccessful installation, you are in the NBN database as having no existing connection, and are very likely to be classified as requiring a new installation not a transfer from POTS to NBN. Which is a whole different (and likely much slower) process.

Your question actually appears to be asking whether you can run VDSL over Cat3. Technically the answer is yes if you want a kilobit per second data connection. Politically the answer is no, as you will then have an illegal connection.

It's possible. Quoting Steve DeRose, "in a pinch you can use 2 spare pairs in a phone wire to run a 10MB Ethernet connection (or possibly higher speed if your cable is better than typical CAT3 phone wire)." Here's a video on how to arrange the pins. The speed you get after auto-negotiation will likely disappoint.

In your comment you indicate this would be for connecting upstream to fiber for which Cat3 is woefully inadequate due to lack of wires and shielding.

Id like to clarify a few terms here:

• FTTN is Fiber to the Node. On the Australian NBN network this is then VDSL from the house to the node
• Your connector may be marked as Cat6 but it's actually 8P8C
• yes, 8P8C can be used to connect a POTS cable to

You will need to make sure you use the punch down spots on the back of your socket, and an RJ11 phone cable might be "wobbly" inside the socket unless you have an appropriate insert for the socket. But you can do it, and in fact this is done fairly commonly in commercial patch panels and installations.

Yes for an improvised RJ11 connection but a solid no for an RJ45 connection.

An RJ45 connection requires 8 wires while an RJ11 connection requires 4 wires.

I mean you can technically wire it up for RJ11 purposes as long as you match the pinouts on both ends of the connector. So it can be used as a janky way of getting an RJ11 connection using existing wiring.

While something like that would be useful for POTS (plain old telephone service) and/or a DSL (digital subscriber line) connection, it’s not useful for things like FTTN (fiber to the node) which you clarify in your comments that you wish to use it for.

And past that, it wouldn’t be useful for everyday/common ethernet networking purposes anyway; just POTS and/or DSL.

The short (and long) answer is NO.

POTS was always run a single cable (4 thin wires, not twisted) so cable aggregation is not possible. Cat6 cable 4 twisted pairs of thick wires in a single shielded cable - twist/shielding to get Cat6 speeds.

The best use of the POTS wire for you could well be as a "fishing" wire to thread a Cat6 Ethernet cable through the house. Otherwise just run new Cat6 cable; it in most cases cheaper than you think and in almost all cases cheaper than trying to "re-use" the old wires.