silly problem which we cannot fathom, the 2400 works fine plugged into the BT master socket, but we now want to move the phone to the other side of the room, and the BT extension (10metres) cable reel that we bought to do this does not quite work properly.

We can make outgoing calls using the 2400, but when someone calls our number the 2400 does not ring - it seems that by using a bog standard cable reel extension that the ringer is not able to work on the 2400

I took the faceplate off the BT NTE and it has a big yellow capacitor, which is good because I think that is what provides the ringing, the cables inside the NTE box are wired to pins 2 and 5, again what I would expect, so I am bit foxed by this one  !

maybe it might be best if I just make a longer cable, does anyone know the pinouts for the RJ11 plug at the Beocom 2400 end of the cable ?

the BT jack end BT431A is simple enough

For older phones to ring they use pin 3 on the extension which is produced from the capacitor in the master socket. So your extension cable must have pins 2, 3 and 5 connected.

trouble is there is no extension socket Keith, just the BT master, we are just plugging in a 10 metre cable reel to the BT master ( NTE ) socket on the wall, and using the cable supplied with the Beocom 2400, when only using the supplied 2 metre cable the phone rings fine, but when we use the 10 metre extension reel between the BT Master and 2400 it does not ring

BT Master -  10mt Cable Reel  -  Beocom 2400

As I said, that's because your 10 metre extension cable does not have pin 3 connected. Modern phones don't need it, but the 2400 does.

ah, so even though the BT Master only has pins 2 and 5 connected, the 2400 needs an extension cable that has 2, 3 an 5 on the RJ11 socket into the bottom of the phone

Keith, I just don't get it how it magically works with the supplied B&O cable if there is no wire even terminated on pin 3 inside the BT master socket ??