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Message 1 of 28

A Few FTTP ONT Queries

Thinking of having FTTP installed and I want to get everything ready in advance so I get a nice, clean job with everything where I want it.  So can anyone tell me:

  1. The fibre ONT has a socket for wired phone(s).  What is the maximum REN it will accept? Is it still 4 as with a copper line?
  2. Am I safe to assume that there is no longer any need for a BT master socket - all the internal wiring is now  plain, secondary sockets daisy chained together?
  3. Can anyone tell me the dimensions of the CSP box that goes on the outside wall and if possible, the pitch of the mounting screws and the the relationship to the hole through the wall to the ONT?  A template would be even better, if anyone has one.
  4. For the forseeable future, are BT continuing to install the Huawei ONT and BBU in a combined box, or are they rushing to a different provider and design?
  5. I have an existing 54mm duct with copper from the cabinet (FTTC).  Is the fibre blown through this duct, or is it pulled through with the copper?  Is the old copper left in the duct?
  6. I want to change the location of of the incoming point when the fibre goes in.  If I buy my own BT duct, bends, etc. and get everything dug in and ready in adavnce (next to the old duct), will this upset the engineer when he turns up or make his dy?

Many thnaks, Ian


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Message 2 of 28

Re: A Few FTTP ONT Queries

Oh, yeah, I forgot #7 - Can I bring the duct up within the house, or does it have to be connected externally, where it could be damaged or cut by some unscrupulous individual?
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Message 3 of 28

Re: A Few FTTP ONT Queries

I think I'll leave this to @Starwire  to answer. I'll tell him to put his tinfoil hat on as well.

Message 4 of 28

Re: A Few FTTP ONT Queries

1. The ONT no longer comes with a phone socket, especially the Nokia one. Some Huawei ones do my Openreach are getting rid of the FVA Service anyway and you’ll either retain your voice service via Copper or be moved onto VOiP.

2. Answered in Q1.

3. CSP is gray as standard. It’s about 7 or 8 inches tall, 5 or 6 inches wide and about an inch deep. Why the fudge you want to know what screws it uses is beyond me?!?!

4. Openreach don’t fit BBU’s anymore.

5. if it’s blown Fibre then it’s blown if it’s Connectorised then it’s pulled.

6. Please don’t messing around with the Openreach Duct Network.

7. No it’s stays outside. You must live in a nice area if your main concern is someone’s going to damage it.

Message 5 of 28

Re: A Few FTTP ONT Queries

Thanks for the replies Starwire.  By way of further explanation and query:

  • If they are no longer installing the combined box of ONT and BBU (HG8110H-20 GPON as per the BT website), what ARE they installing and what are the dimensions and critical screw fastening points?


  • Is there any link to what they ARE installing which has some technical details I can use?


  • I didn't ask about screws, I asked about screw positions.  I'm about to have the exterior of the house re-rendered in some of that fancy stuff you always see on Grand Designs. I want to make sure that

a) there is room for the CSP where I want it to go ... and ....

b) if I can get the hole dimensions beforehand I can pre-drill them so that somebody with a big SDS and another 7 installs to do that day doesn't hurt my render at over twenty quid a square meter.


  • If they don't fit BBUs, what happens to my phone connection when the power goes off (as it does regularly here, since we are in a group of 12 houses supplied by lines across a field)?  Even if it's VoIP, it needs power to call for an ambulance when I fall and dislocate my shoulder (again).


  • Your answer to 5 is technically 100% accurate but in practical terms tells me nothing.  Sorry.


  • No plan to touch the duct network, see original question.  I was planning to lay pre-prepared duct work adjacent to the existing, just the same as I would be putting in duct work if I was doing a self-build.  I still need to know if this is approved or frowned upon.  More importantly, if I don't do it is an installation engineer going to put in an extra 3m or so of new duct?  At no additional cost?


  • Damage is not anywhere close to my main concern.  However, if I was planning to sneak up in the middle of the night to pinch my Aston Martin, I'd start off by cutting the network connection for cameras to the security company.  Also, a big expanse of expensive, self-coloured, monocouche render doesn't look so great with a grey CSP box and half a meter if BT duct capping planted on it. Duct into the house is preferable. 


All I'm looking to do here is get everything prepared in advance, for cable entries to go exactly where I want them, visible stuff exactly where I want it, internal phone wiring and RJ45 sockets for the network exactly where I want them and a finished job that looks like it was done by a professional, not an ape.  That's not to denigrate any Openreach engineer, but if you saw what I'm replacing you'd think that Ray Charles installed it.

Of course, al of this would be much easier if I had the option to speak to an Openreach engineer prior to placing an order but the only way mere mortals can make contact is via a seance.  It's easier to get in touch with Lord Lucan.


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Message 6 of 28

Re: A Few FTTP ONT Queries

You will be able to liase with the install engineer on his arrival and most will try to meet your needs unless it would cause a problem. They will advise though.

The install is free even if they have to dig up from the pole to your property. It just means the install will be delayed until that is completed.

I fail to see how drilling a couple of holes would affect your fancy rendering, if it does it's not fancy enough.

There is no BBU suppied now, if you want a back up, get your own.

You have a choice of 2 colours of CSP, grey or grey. Get some paint if you want it another colour.

There may be a valid reason for the cable entry not to go where you want it, if so the engineer will tell you why. Like it or lump it or cancel.

Any internal wiring from the ONT is your responsibility not Openreaches.

Here is an idea of the ONT being fitted now.fttp_small_ont_2019.jpg

Please note, I do not work for BT or Openreach. All comments are my own and do not reflect any policy of either company. I just tell it how it is.

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Message 7 of 28

Re: A Few FTTP ONT Queries

That ONT image appears to have a Tel port.  That's different to the previous reply.  Who's right?

Yes, I know the CSP is grey.  See previous post.

Yes, I know internal wiring is my responsibility, that's what I'm trying to prepare for.  See previous post.

I've done some liaising with installation engineers in the past.  Been there, done that, bought the tee shirt.  One engineer's  valid reason for not accommodating a preference is is someone else's CBA (refer to Urban Dictionary for definition).  See previous post w.r.t. another 7 installs to do same day.

Sadly, I'm not surprised that BT still have all the combined ONT/BBU info on website (e.g. and in the more detailed deployment manuals and Openreach developer manuals, only to then find that BBU is no longer supplied.  

It's just a pity that no-one could give me the detailed info on what they are actually installing today, rather than making sarky comments about my objectives.  Clue - is it the Nokia modem, does it have a model number, is Hauwei now personae non gratae?  See previous post.

I fail to see why people can't just read a question and either answer it or else wind their neck in, move on and not bother with the judgements and spurious comments.   As you, I just say it as it is.

p.s the CSP is in fact also available in white, although to the best of my knowledge the ugly capping is still either grey or grey.



Message 8 of 28

Re: A Few FTTP ONT Queries

The older CSP’s used for the Blown Fibre Tubing came in a choice of White/Grey/Brown but Openreach has stopped using them in favour of just on CSP, which is the new bigger grey one.

The Engineer may have an older one but probably not as Openreach stopped using them some time ago.

Ref to the ONT having a TELE Port, that is for Openreaches Fibre Voice Access Service only, which they are stopping very soon. They are using up their existing stock of Huawei ONT’s that have a TELE Port but the new ones won’t have one and the Nokia ONT’s don’t have one at all.

I’ve been told BT are going to supply BBU’s to those that need them on their VOiP Service, I’ve not actually seen one yet though.

Message 9 of 28

Re: A Few FTTP ONT Queries

I don't have much to have to the other comments here which completely mirror my recent experience, but I have to say that I'm on my third FTTP install since 2010(ish), and I've always been really impressed with the way Openreach have thoughtfully and logically evolved their install process over time (my latest install in July has the ONT as pictured in the image). My engineer was open to discussion about where the fibre cable entered, but in the end I elected to have the ONT at the normal point of entry for my previous copper cables and then run ethernet cables internally between the ONT and my BT SmartHub which was placed for best WiFi signal, (also, my thinking was much like you yours, I didn't want 20 feet of easily vandalised fibre cable running down the outside of my house, especially with my priceless Vauxhall Viva parked on the drive with its keys in the dish on the dresser right by the front door 🙂

Only other advice I can add is to provide your Openreach engineer lots of tea and nice biscuits (Jamie Dodgers, not sh*t ones like Rich Tea!)

Good luck!

Message 10 of 28

Re: A Few FTTP ONT Queries

You do realise that beside the plastic outer cover there is also a Kevlar inner cover? You know, the stuff they make bullet proof vests out of.

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