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

[Epona18]

I've recently moved to BT and set up my first Digital Voice connection and my old number has ported over fine and all is working. We use an old corded phone downstairs connected to the Smart hub via the green socket, and an old corded phone upstairs connected to the adapter we were sent with the Smart hub. I'll try to be clear as to my issue.

I wanted to changed the RJ11 cord for the phone downstairs to the hub as it's a bit old and manky(to put it mildly!). I bought one and it didn't work, no dial tone, nothing. I thought it was faulty and returned it and bought a different brand. And the same thing, no dial tone, nothing. But then when I put back the old cable again this time, there was no dial tone with the old one either. 

I phoned it via my mobile and the phone still rang but although the person could hear my voice, I couldn't hear them. The phone upstairs on the adapter still had a dial tone so wasn't affected. So the only thing I could think to do was to reboot the hub, and when I plugged the old cord back in, I did get the dial tone back.

That got me thinking of rebooting the hub and then trying the new RJ11 extension cable again, but it still didn't give a dial tone. I then had to reboot the hub to get a dial tone back on the old cable. I did try plugging in a different corded phone to the hub and that didn't work either. I just don't have a clue as to why.

I'm not very technical and just about get by, but do I need to do something within the hub settings? I see that although it's an old corded phone that it's registered as handset 1. Is the new RJ11 cable not recognized for some reason? Or do I have a second bad cable and need to return it?

I don't want to fiddle around blindly too much and leave us with nothing as my elderly Mum doesn't have a mobile phone so only uses the landline. Any suggestions in simple language as to why the new cable isn't working, or why the other corded phone I tried to plug in didn't work, would be really helpful. It would be nice to get rid of the old cable, but so far it's the only thing that works. 

[WSH]

Unfortunately, wiring on RJ11’s can vary with what they were intended for.

For a phone lead it should be BT plug pin 2 to RJ11 pin 4 and BT plug pin 5 to RJ11 pin 3.  (That’s viewed with the plug pins facing you and the lead hanging down.  Pins positions are numbered 1 to 6, left to right, including any missing pin positions).

Be aware, the Smart Hub does not support the old “bell wire” required by very (very) old phones.  Some of the old micro-filters simulate this wire and so will correct the non-ringing problem.  (Although I don’t think that is the problem here from your description).

[Epona18]

I will sound thick here, but what does the comments about pin numbers in the plugs have to do with anything and why should I be counting them and which bits do I count? The copper parts or all of the gaps too? The RJ11 cables I bought were brand new. Unless you mean I have to match up the pins to the same numbers as the older cable that does work? When I bought the cables brand new there was no pin count to choose.

Also, why does the old phone and cable work, but another phone I tried to plug in with it's own cable didn't?

[imjolly]

The cables appear the same but the pin configuration can be different and that is probably the cause of your problem so you need to check the wiring od existing cable is identical to new cable.

[Epona18]

I'll have a look tomorrow when I'm back downstairs and can compare cables in a good light. I'm not sure where the heck I'd buy a cable with specific pin arrangement though, none of the places I looked said anything about pin count.

That also doesn't explain why the old cable then didn't work and I had to reboot the hub to get service back on it again, though. Nor why the other phone I tried didn't work on its own cable either.  Surely the green socket on the hub can't be that ridiculous?

[Anonymous]

See this post to check if the issue is the wrong cable:

https://community.bt.com/t5/BT-Devices/BT4500-phone-problem-compatibility/m-p/2325721#M31055

Once you know what you need, you can just search for straight or crossover cable. Some retailers sell a cable with an adapter, so you have both bases covered. IIRC, Currys is one.

[Epona18]

Thanks for that link. It might help with the original phone, but it doesn't explain why the other phone didn't work plugged into the green socket on its own original cable, though. It had it's own RJ11 end and the standard BT end. And still doesn't explain why the original phone stopped working when I put it back, until I rebooted the hub. It has to be some sort of registration recognition thing too, doesn't it?

[WSH]

As imjolly said, the implication is that the cable isn’t wired the same way as the old one.

Take a close look at your old lead.  Can you see the wire colours at each end?  Then just write down what’s connected to what pin and get a matching lead.  Old phones were straight-through.  More modern are crossover.

[Epona18]

I will definitely give it a look tomorrow and if it is a different cable configuration, then I will order appropriately and try that. 👍 

[licquorice]

Phone leads aren't RJ11, they are BT431.

As others have said, the leads need to be wired correctly.