This topic

BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 10:30:39 GMT

I don't know whether this type of question can be answered here but it concerns the various colours of the wires that are crimped into those male BT plugs found on landline phones and extension leads etc.

I dissected one old lead and the colours were, L to R, White, Green, Blue, Pink.

I wish to alter my existing extension lead, which at the moment terminates in a multi socket adapter with the springy lever plug moulded into the back. It is this lead I'd like to plug into my Smart Hub 2 for DV when the time comes and a bulky adapter type would be impractical so would like to fit a simple BT plug.

I can't see how I could ascertain easily if this lead has a different colourway as the lead does not enter the plug directly but enters the adapter body. Even if I strip back a bit of the insulation I might see different wire colours that don't correspond to how they'd enter the 4 pin plugs and crimper I've ordered from eBay.

This may sound very confusing and for that I'm sorry. Basically I'll just want to cut of this clumsy adapter 'plug' and replace it with a simple BT plug.

Re: BT socket plugs on phones /Extension leads etc.

jac_95 — Fri, 06 Oct 2023 10:47:06 GMT

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Re: BT socket plugs on phones /Extension leads etc.

WSH — Fri, 06 Oct 2023 10:58:55 GMT

Unfortunately, phone extension wiring is nowhere near standardised like network wiring.

I'm just a customer, like yourself, so someone here may have a much better solution but if you have cut off the “bulky adapter”, I’d use a multimeter to connect what is left of the wires on that adapter to pins 2 and 5 on the plug bit and see what colours connected to where. (Unless you have very old phone equipment, 2 and 5 are the only ones you need to worry about).

As another idea, make up a straight through lead with a BT 431 phone plug at each end, (i.e. pin 2 to pin 2, pin 5 to pin 5 etc.) Plug one end into the multisocket adapter and the other into the SH2.

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 12:41:56 GMT

Thanks but you refer to pin 5 when there are only 4 pins, surely in a 431 plug? Anyway I've ordered a pack of 10 431s from ebay so maybe I jumped the gun.

I might end up by just moving the b...... y DECT phone into the room where the BT hub 2 is and then put the 'satellite' phone in there to where the DECT phone plus base station was . Just interchange them. Grrrh.

Re: BT socket plugs on phones /Extension leads etc.

Anonymous — Fri, 06 Oct 2023 13:02:52 GMT

BT 431a has six pins but 1 & 6 are never used. Most dispense with pins 1 & 6 entirely to just leave 2-5 present, but the missing pins still retain their number.

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 13:26:38 GMT

Thanks. I was just thinking about feeding the 4 bared conductors into position in the plug expecting them to feed into the appropriate positions which in your explanation will be pins 2 to 5 without fear of going into the wrong position.

Re: BT socket plugs on phones /Extension leads etc.

WSH — Fri, 06 Oct 2023 14:22:41 GMT

I would not assume they are wired that way at the other end if I were you, but most modern kit does not mind if 2 and 5 are reversed.

(Sorry, I should have explained why they are called 2 and 5 earlier).

Re: BT socket plugs on phones /Extension leads etc.

WSH — Fri, 06 Oct 2023 14:33:08 GMT

I've also just spotted your comment about "bared conductors".

Using bared wires will probably short. Those type of plugs are IDC (Insulation Displacement Connectors). You put the wires in with the plastic still on and the pins punch through the plastic when crimped.

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 15:05:02 GMT

Oh, that's unsettling then as a long term YouTube bloke 'My Mate Vince' has 9 year old video rewiring said plug. He removes outer sleeve of cable then with his universal cable tool removes a few mms of inner sleeve from each coloured wire before insertion to the tips of the four Gold sleeves, then crimps them with same tool.

At that time all his work was with Telecom stuff and assumed he was a BT engineer or whatever.

Still in my time though I've wired a few extension wall sockets and remember just using a push down plastic tool to secure covered conductors in place.

Am really confused now.

Re: BT socket plugs on phones /Extension leads etc.

WSH — Fri, 06 Oct 2023 18:21:30 GMT

I suggest you watch the video again.

I've just watched it and what he demonstrates is exactly what I've said. If you watch carefully, he strips the outer sheath back. He does not strip the inner insulation off the wires.

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 19:34:32 GMT

Really? I'll have to watch it again on my large TV this time and sit close.

I'll report back!

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Fri, 06 Oct 2023 19:56:57 GMT

Oh goodness me, you are correct. Yes he does just strip off the outer covering and insert the conductors as they are. Thus explains what I said earlier about wiring up sockets bby just pressing down the leads directly into their correct positions.

Many thanks for drawing my attention to my error and inattention when looking at videos like this.

Regards

Nick

Re: BT socket plugs on phones /Extension leads etc.

tonyowen — Wed, 14 Oct 2026 13:38:08 GMT

A slightly different slant on the question - a BT plug is fitted to a smarthub3. the cable with the BT plug at its end is then wired [from the back] into a standard BT socket into which a landline is fitted. BUT the landline phone does not connect. To which terminals on the BT socket should the wires on the BT plug ended cable be fitted? [ie the standard is pin 2 white, pin 3 green, pin 4 blue, pin 5 red/pink]

Re: BT socket plugs on phones /Extension leads etc.

WSH — Wed, 14 Oct 2026 14:42:39 GMT

Modern equipment only needs BT plug pins 2 and 5. Pin 3 is redundant. Pin 4 is the old “bell wire” to ring the bell on very old phones. Modern equipment doesn’t need it, and it can be a source of interference on an FTTC connection. Modern equipment also tends not to be polarity sensitive, so pins 2 and 5 should work either way round.

Colour schemes vary a lot with manufacturer. Your best bet is to use the old lead to test what connects to what and then make up the new lead accordingly.

EDIT: I've just re-read your post and you ask about the socket. Whereas in IT plugs and sockets are numbered the same way, BT traditionally numbered sockets as a mirror of the plug pins. This website might help with sockets:

https://telephonesuk.org.uk/wiring-info/

Re: BT socket plugs on phones /Extension leads etc.

gg30340 — Wed, 14 Oct 2026 14:33:20 GMT

@tonyowen

If you are seeking an answer to an issue I will move your post onto its own thread rather than you jumping onto some other persons thread which may cause some confusion.

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Wed, 14 Oct 2026 14:45:18 GMT

I agree with that, In the past I have cut several different cable types only to find inconsistence with colourways. Best to hold the plug with steady and cut the wire or at least remove the outer sheath and note which colour are present and the order left to right.
May sound obvious I know but it works.

Re: BT socket plugs on phones /Extension leads etc.

WSH — Wed, 14 Oct 2026 14:56:12 GMT

@HHGTTG On a different topic, how long is this ethernet cable you need? I've just been out to do the shopping and Asda are selling 5m cables, £7.50

Re: BT socket plugs on phones /Extension leads etc.

HHGTTG — Wed, 14 Oct 2026 15:11:40 GMT

I had already bought that length from ebay months ago but the ONT is further away from my original desired position for it. The 'engineer' said an alternative position was better as it reduced the amount of external wire showing which is good. Therefore my current length is too short and I just really want to put one ethernet adapter and my 5m cable onto existing white cable fitted by Openreach (Kelly) rather than fiddle around on my ancient knees and back trying to locate socket on ONT. It's early days and I am always anxious especially as i phone in now DV and no longer independent of the SH2.

Re: BT socket plugs on phones /Extension leads etc.

WSH — Wed, 14 Oct 2026 15:17:47 GMT

If you insist on doing it as an extension, have a look on Amazon for cat 5e female/female couplers. I doubt you'll get an extension lead for cat 5e. I've never seen one.

Re: BT socket plugs on phones /Extension leads etc.

chrisjp — Wed, 14 Oct 2026 15:58:23 GMT

"I wish to alter my existing extension lead, which at the moment terminates in a multi socket adapter with the springy lever plug moulded into the back. It is this lead I'd like to plug into my Smart Hub 2 for DV when the time comes and a bulky adapter type would be impractical so would like to fit a simple BT plug. "

Much easier just to buy a new lead with the appropriate plugs at each end - a BT standard plug at one end, and probably an RJ11 plug at the other to connect to your phone. A quick search on Amazon will provide lots of choices of lead length and with usually sub £10 prices and next day delivery.
Much easier than messing around baring cables and trying to crimp them into a small plug!