Line Box Rearrangement

27 Apr 2009
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United Kingdom
Help needed. Before I call out BT at significant cost can someone advise me on a relatively simple (i.e. if you are not a telecoms idiot like me) problem.
Up until a week ago I had 2 BT lines, 1 into the house and 1 to an office in the garden. Having now retired I no longer needed the separate line to the office & hence have discontinued its use. It would be useful however to have the office telephone connected as an extension to my remaining line.
Within the external line box ( square cream coloured ) the incoming BT line is connected with white & orange wires to my house phone and black & green wires to my outside office phone. To effect the office phone as an extension is it possible to just connect it to the white/orange wires?
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It'll work yes, a few things to bear in mind though.

1: you aren't really meant to touch equipment before the master socket, however BT are unlikely to make a fuss about it unless you break something and then call them out.
2: I have heard some reports of BTs line measuring equipment getting confused by more than one master socket on a line and people being denied broadband beause of this. I dunno if this is true or not.
3: if you have broadband you will have to make sure all phones are behind a filter. If you are in a marginal area the extra brancing in the phone wiring may also cause broadband issues.
Having two master sockets on a line can cause issues when line tests are done (the next time you dial 150 and report a line fault).

If you have a 3 pair cable (likely) from the joint box to the working master socket you can use the remaining two pairs (unused) as extension wiring from the mastersocket back to your jointbox and then join these to the cable running to the second socket.

Then change the second socket for a secondary rather than a master.
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Thanks very much guys. Unfortunately the cable from the joint box to the master socket is only 2 pair & given that I apparently need 3 wires for the extension unfortunately the option to use the spare wires does not seem to be on. Nevertheless you have given me sufficient advice to think about possible solutions for which I am grateful.

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