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Connections for a UK dial-up modem cable?

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PeteWeedon

Technical User
Dec 29, 2002
464
GB
Hi,

Please can any (UK) Tek-Tipper tell me the correct connections between the BT431A plug (goes in the wall phone socket) and the RJ10 connector that plugs into the line jack on the modem?

Gracie was working on a client's computer recently. The client's modem cable had been cut and joined with the join covered in masking tape so we substituted another cable. This allowed the modem to dial out OK but, unbeknown to us, it stopped the house phones from ringing on incoming calls. On outgoing calls, while that cable was plugged in to the phone extension socket (jack), the side-tone had a strange hollow echoing sound.

The client's original cable only had 2 poles connected at each end but I didn't have an opportunity to buzz the cable through before the computer had to be returned to the client. Our substitute cable (now in quarantine) has four poles connected as follows:

My definition of pole numbers may be non-standard, I've counted from left to right with the contacts facing me and the cable leaving the plug at the bottom.

RJ11 pole-1 no connection
RJ11 pole-2 black BT431A pole-4
RJ11 pole-3 red BT431A pole-2
RJ11 pole-4 green BT431A pole-5
RJ11 pole-5 yellow BT431A pole-3
RJ11 pole-6 no connection

I've examined a dial-up modem and seen that only poles #3 & #4 are used. I've also done a Google search on 'modem cable' but only found cables for sale, nothing on wiring details.

Any help, direct or links, will be appreciated.

Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!
 
I've found that pinouts on the RJ11 end vary but the BT connection is alwayw pins 2,3,& 5. The A & B legs are on 2 & 5 the bell circuit is on 3
 
pins 2 and 5 on the bt plug end to 3 and 4 on the modem end

It's not getting any smarter out there. You have to come to terms with stupidity, and make it work for you.
 
Just managed to get in to TT, been inaccessible all day!!

Thank you all for your inputs, I'll explore the links tomorrow.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!
 
Just one thing more:

Did I get the pole numbering system right?


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!
 
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