Can't get DV to work with new RJ11 extension cable to corded phone

[Epona18]

The photo is of my old cable. We've established that it's straight, that's not in question now.

The Amazon option was something I was looking at because it's cheaper, as I don't pay postage on Prime and if I have to return it they get Royal Mail to collect from my house for free...which is very helpful, not being able to walk far. There doesn't seem to be any harm ordering it and seeing if it is as it appears in the product photo(I know not to always trust photos)... I can return it for free if it's just another crossover, then order from Currys, and I'm in no worse a position. The Currys one has bad reviews which is off-putting, although that could just be people with the wrong compatibility. 

[HHGTTG]

@WSH  you can always carefully strip back of the outer part of said cable about an inch or so where it goes into the BT431A plug and see what the colours of the conductors are from L to R with say the plastic clip on the right hand side. I've done this with several and there are different colours on a new 10M extension lead I bought compared to an old one. They were however in the same places.

I know this isn't the problem here unless one is termination one's own lead with a BT socket plug.

[HHGTTG]

@Epona18 

Is that a BT 431a plug? Never seen a transparent one before! Or is that the plug that goes into the phone end?

[Epona18]

I've seen both transparent and white plastic... I'm confused on which end is which, but the photo is of the smaller end that goes into the phone's base. Is that the B431A end? Anyway, it's the smaller of the two plugs in the photo.

[WSH]

@HHGTTG   As I said, the electricity is colour blind, it's what is connected to what that is the issue.

And BT plugs do have a small inspection window left just before the pins.  Trouble is it's usually obscured by plastic swarf left over from the moulding.  If it's clear, you can see the colour of the wires.

[licquorice]

RJ11 plugs into the phone, BT431 plugs into the hub.

[HHGTTG]

Here a plug I made earlier i.e BT431A

A cut off plug from new lead

[WSH]

@HHGTTG  Very nice but isn't it going to be a bit short when you put the plug on the other end?  (Ha Ha).

Anyway, you should be able to glimpse the colour of the wires through that slot behind the pins.

[HHGTTG]

@WSH

Well I find very difficult seeing the colours in situ. Perhaps a magnifying glass would help. I have another cut off plug with different colourway. 

[Epona18]

An update:

I bought the Currys cable, arrived today, fitted up and seems to be working all as it should be. 👍 Phew! Glad that's sorted out.

Thanks for pointing me(eventually 😃) in the right direction and helping out this technologically challenged thickie. 😀