Problems with Legacy phones after connection to FTTP

[foxtoncarl]

I have FTTP with a Smart Hub 2 but need to continue to use my legacy (non-digital) BT Big Button house phones due to poor eyesight. (I am 86). I have found that they don't work with the BT digital voice adapters and in any case these are inconvenient due to difficulty with access to power sockets. I have connected the hub to my BT ADSL V1.0 Master Socket using a double ended BT 431A jack cable as advised on the forum. (Using a splitter in order to be able to also plug one phone into the master socket (having disconnected the redundant exterior phone line from terminals A and B as advised on the forum). However only this phone rings on an incoming call although all three of our phones can make and receive calls, and all have a dial tone (intermittant if voice mail messages have been received, requiring a call to 1571 to listen and then delete). This result was obtained with Orange?White connted to 2 and Blue/White connected to 5 (or vice versa). Adding White?Blue cable to 3 caused all phones to ring but extension phones (apart from the one to the splitter) have no dial tone and cannot make or receive calls. Other cable combinations don't seem to work eith. Any solutions anyone?

[jac_95]

Hi foxtoncarl,

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[Tev]

Hi Foxtoncarl

I would suggest that from your description of the wiring, you have connected it incorrectly.

Was it  wired as you have stated originally? as the correct wiring should have been 'blue with white rings' on IDC2, 'white with blue rings' on IDC5 and 'orange with white rings' on IDC3, there should be no other wires connected to any other IDC 's. The same wiring should appear at all other phone sockets. If you have it connected as you stated at the main socket, but connected correctly at the extensions, then you will have exactly the symptoms described.

Just as an aside, all the BT431/631A double ended cords I have seen actually have a reversal, ie pins 1-6 at one end appear as pins 6-1 at the other. This is not a problem normally as a pin 2 & 5 reversal would make no difference, however a pin 3&4 reversal would remove the ring capacitor from the SH2 at the other end, and if you were relying on it to ring legacy phones, they wouldn't work. However as you are still using the existing main socket, which has a ring capacitor in it, this will recreate it and the system should still work with legacy phones.

Terry

[foxtoncarl]

Thanks very much for that Terry - I think I have checked all the wiring permutations, including the one you say is correct, without success but will check again in a couple of weeks time when  return from holiday. wiring is difficult for me due to limited vision and  will explain in due course why I'm not absolutely sure the master socket had correct wiring in the first place. another considertion I wonder about is whether the problem lies in my having an ADSL V1.0  socket instead of a standard master socket? The original post I followed in trying to solve the problem only states connect the 'master socket' to the phone socket on the SH2 with a double ended phone lead which i did with the resulting prolem I posted. could this be the the cause and do I need to replace the ASDL V1.0 with a standard extension circuit master socket? In the meantime, thanks for your help . Carl

[licquorice]

It doesn't matter that you have filtered socket rather than an ordinary master socket as you are connecting to the unfiltered phone socket rather than the broadband socket. 

The actual colour of the wiring obviously doesn't matter, you just need to ensure that terminals,  2, 3 and 5 in the master connect to terminals 2, 3 and 5 respectively in the extension socket

[Tev]

Hi Licquorice

I agree with your first paragraph, it shouldn't make a difference whether the master socket is filtered or unfiltered.

Your second comment I am not so certain. It surely would be better to use a twisted pair for the speech circuit, ie IDC2&5 to avoid induced noise from long adjacent cable runs, possibly mains cables or RF interference. I remember about 30 years ago testing some old 4 wire cable (blue,orange, green,brown)  for crosstalk. The wires didn't seem to be twisted into pairs, or if they were the lay length was very long, the crosstalk between any selected pairs at audio frequencies was about 40dB from memory. Also I would suggest it would be better to follow accepted wiring convention to avoid problems if the installation is extended.

Terry

[licquorice]

Agreed, but I didn't want to confuse the op further.

[foxtoncarl · Accepted solution]

Hello Terry, I've just been able to re- check the wiring before going away and it appears that your mention of the extension sockets needing to have the same wiring as the main socket soved the problem! It seems that they were  incorrectly wired 30 years ago by the builders with Orange/White = 2    Blue/White =3 and  White/Orange = 5.  This was one of the few combinations I hadn't tried after the wires came out of the master socket when I took the back plate off the wall to disconnect Termianls A & B from the outside wiring and I hadn't made a note of their colours. On replicating this sequence at the master socket 'Bingo' - all the extensions, and the hall phone - plugged into the splitter into the main socket (in the hall),  and also connecting it to the SH2, now ring and can make and receive calls.. Thank you very much for your invaluable help and also all the other members who posted information. Hopefuly I won't need to trouble BT further. Carl