I remember doing multiplexing in a BTEC Telecoms unit in the 80s as a student and its only just started to be deployed!

Multiplexing is still used today, in fact the modern [or even the old] PC`s still use it.
It is not just being deployed, it has always been a part of nearly all microelectronic systems.
The same could be said for high and low pass filters, transistors, inductors etc.
It`s just a recipe like cooking.
BTW I am 77, but still enjoy messing with a hot soldering iron.

Morning Robertos

Agreed that the original pair must be cut at some time during the operation, to achieve the diversion to the FTTC.

If they are cut at the start, then basically there would be no Voice Phone Service until the end of the operation, say a loss of about 5 minutes.

By leaving that "disconnecting them from each other" to the end, there is no interruption to the Voice Phone Service at any time.

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When I watched my own line being upgraded from ADSL to VDSL, in June 2014, arriving at the PCP just as the 17070 call was confirming that the technician had found my D-side pair correctly, he than selected the FTTC dual link pairs "some how" at the opposite top corner of the PCP - where I was standing to the right, the PCP right-hand side wall hid that area.

He ran two twisted pairs from that corner across to the left, to my D-side pair. Those two pairs were new "off the reel".

Again I did not see exactly how he connected to the FTTC "tails" because of the PCP side wall.

At this stage, there had been no interruption to part the E-side from my D-side.

He connected those two short pairs (say about 2 feet long) to my D-side, paired and colour to colour, about two inches apart, using Gel Crimps, so still no break in Phone Service.

Having done that, he then cut out each of those two inch lengths, thus effectively diverting the Exchange line out to the FTTC, merging in the VDSL signals; and returning to the PCP , then heading out to my house.

Tidied up the new, off-the-reel pairs etc to run across the inside of the top of the PCP; picked up the "two inch" fragments and some other odds and ends; and closed the cabinet.

That is, there was no break in the original, probably-1967 wiring, until the very last moment.


If I had been using the phone in my house, I doubt if I would have noticed any of the work apart from the 17070 call, as effectively there was no time when that continuity was interrupted.

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Hence as the original OP continued to have Phone Service, I suggested the possibility of the final cutting and thus diversion being omitted.


There is also the chance that the technician got the respective colour from pairs mixed up - although I am doubtful of that.

Morning Banger

"Multiplexing" was being used and taught back in the 1950s - and was far from new then.

Edited by deleted (Wed 25-Mar-15 07:18:20)

I don't know if that's what it is called in this scenario, but that's the function.

'FTTC ties' is the accepted parlance for those who work on them.

The question that arises in my mind - Is there a specific link/VDSL filter point (pre-) allocated remotely within the FTTC?

Yes ! When a customer orders an FTTC service, Openreach will allocate one of the ties from the FTTC DSLAM and build it's remote path to Btw/Sky/Talktalk.

So if the installer connects the punters voice service through an incorrect port then there is a good chance the punter will end up with no (internet) service at all. The filters will stop the original ADSL, and the wrong FTTC ties will give no sync/no PPP dependant on what it's current configuration is.

Not all the ties are live (produce sync) when not in use. I guess theres a slim chance that the punter has ordered through BT broadband, and then gets another BT Broadband configured tie, that'd work, but still would be technically incorrect.

As for the OP, without further details it's going to be hard to establish what the cause was ..... wrong ties, incorrectly built ties, faulty ties, incorrectly jumped ties ..... the list goes on.

Jeez, the installer made a meal of doing your line ! No wonder you seem a little confused

Find your E-side, cut down and verify the number, trace the jumper to the D-side (whilst doing this you can be verifying sync on your allocated ties) run a new jumper from the E to the FTTC in ties, check dial tone is coming out of the FTTC out ties, and jumper this to your recently discovered D side.

I'm not sure if that technically covers your question, but AIUI it is not up to the engineer just to connect using any he wishes.

Correct, you need to be doing an FTTP installation to have that luxury.

"Find your E-side, cut down and verify the number"
- He must have done that to get the correct number returned on his 17070 call, using temporary gel crimps to connect his Test Phone, without cutting/snipping any wires.


" trace the jumper to the D-side (whilst doing this you can be verifying sync on your allocated ties)"
- This may have been part of the operation hidden by the PCP side wall or panel.


"run a new jumper from the E to the FTTC in ties"
- First of the pair of the two new link pairs, taken fresh of the reel


"check dial tone is coming out of the FTTC out ties"
- This may have been part of the operation hidden by the PCP side wall or panel.


"and jumper this to your recently discovered D side."
- Second of the pair of the two new link pairs, taken fresh of the reel



Then finally cutting out the short 2 inch lengths, including his temporary connection, between the FTTC links.



He seems to have followed almost exactly what you describe, apart from leaving the "cut-down" to the last - thus maintaining basic Phone Services working continuously throughout the whole operation.

Thanks for all the interest shown, makes good reading!

For the record I was with Talktalk (no problems but I wanted fibre which only BT offered at the moment).

When the engineer connected his kit to my master socket he said there was no broadband signal at all.
Phone was swapped at 13:15 on Friday and existing broadband stopped working, I got text from BT at 15:50 saying all was up and running. Help line to foreign parts insisted that I wait until midnight despite the text message! Monday engineer appointment failed to turn up because it had not been passed to UK from India. Finally got it all working Tuesday p.m.