Is this slow BB caused by 40-yr-old wiring?

Please could you TBB experts help me to help our friends whose BT BB has slowed to a crawl in recent months? TBB speed check gives 0.34Mbps and they have the odd crackle on their phone line.

The house is 45 yrs old and they believe the wiring is original. An armoured underground cable emerges below the garage wall and enters a circular junction box marked BT NO 18SSA GPO. The contacts therein are corroded and there is much insect debris. The underground cable carries four conductors, green and black being unused, blue and orange entering a four-core grey cable which I have seen normally used for interiors. This cable's outer plastic sheathing is broken in many places, exposing the core conductors, as it runs along the outside of the garage and through the eaves into the roof space.

Somewhere up there must be a junction as one cable re-emerges to run around the outside of the house before going through a window frame to feed a phone extension. The Home Hub is plugged into another extension socket in the office. These sockets are both extension type about 85mm square; there is no BT master socket in the house.

The HH stats are: Line state down 283Kbps, up 888.
VPI 0/38
Modulation ITU-T G.992.5 Interleaved
Noise margin 15.1/13.8dB
Line attenuation 35.5/19dB
Output power 0.0/12.8dBm
Loss of framing (local) 0 Signal 0 Power 0
FEC errors 116/4294967228

Am I correct in thinking the poor wiring is to blame for this? I think it would be best to call BT and have their engineer renew wiring from the round socket to the office, fit a new master socket, and scrap the existing tangle. My friends are happy to pay for this if necessary once they had seen the state of the box and wiring.

It surely cannot be helping.

Just out of interest: would the BT NO 18SSA GPO box be the demarcation point in this case?

Isn't the demarcation point always a socket, not a junction box?

I agree that the grey cable can't be helping - especially if the cores are exposed. There might be other faults with the line, but you'll never be able to tell until that section is ruled out.

In reply to a post by WWWombat:

Isn't the demarcation point always a socket, not a junction box?

I was just curious since in this case there are two extension sockets linked to perhaps another junction in the roof space and the OP says there doesn't appear to be a NTE5 in the house

No, that's the equivalent of a BT66. Most likely, there is no demarcation point, since it ought to be the first point on the feed where the external cable comes in.

In reply to a post by Malwaremike:

Am I correct in thinking the poor wiring is to blame for this? I think it would be best to call BT and have their engineer renew wiring from the round socket to the office, fit a new master socket, and scrap the existing tangle. My friends are happy to pay for this if necessary once they had seen the state of the box and wiring.

As Zarjaz says, the wiring can't be helping. Some photos would be fun.

In reply to a post by Zarjaz:

No, that's the equivalent of a BT66. Most likely, there is no demarcation point, since it ought to be the first point on the feed where the external cable comes in.

Definitely a job for OR then: new cable from the BT NO 18SSA GPO (and possibly even replace that?) to a NTE5 in the office. Then the extension could be wired from the NTE5 to the other room by anybody...

Cut back on the UG feed also, get rid of the breaks in insulation on the incoming pair, loose the current corroded terminals in the bakelite box. New feed to a single NTE where required, jobs a good 'un.

Might (?) get the job done for free since the OP said there 's the "odd crackle" on voice

I seriously doubt that, unless that is the cause. Best bet would be for the OP to take the issue up with the BB CP.

In reply to a post by 4M2:

Just out of interest: would the BT NO 18SSA GPO box be the demarcation point in this case?

nope, there isn't one. It's all BT wiring.

they should get 10M or more on that attenuation, so something is indeed adrift.

If there's crackling on the line it points to a reportable voice fault.

A broadband SFI visit should get an NTE5 and rationalisation of extensions to allow normal service to be resumed. The upstream is full tilt with margin to spare.

Thanks everyone for your helpful comments. I rang BT on behalf of my friends; their (Indian) operator was very helpful and arranged an engineer's visit on Monday. Will post the outcome next week.

BT engineer Tom arrived the next working day after my call. He agreed the line was in a very bad way, it was indeed interior cable and the junction box from the underground was at least 40 years old. He replaced the lot, and installed an NTE 5 box within the home, a very neat job. After testing he assured me that the connection was excellent and the phone is now noiseless.

Alas the BB is even slower, falling from 0.3Mbps to 0.1. After an hour's connection the Home Hub stats are little changed from the OP:
Line state down 283Kbps, up 888 (unchanged)
Noise margin 15.1/13.8dB before, 21.1/13 after
Line attenuation 35.5/19dB before, 34.5/18.6 after
Output power 0.0/12.8dBm before, 0.12.8 after
Loss of framing (local) 0 Signal 0 Power 0
FEC errors 116/4294967228 before, 116/4294967232 after

Being rather despondent I took my friends' HH and cabling to my own house where it worked perfectly, attaining my usual speeds. I understand the exchange should adjust the line state, will it really take a week of constant connection? Or is it likely the profile is stuck, requiring a call to support?

In reply to a post by Malwaremike:

Line state down 283Kbps, up 888 (unchanged)
Noise margin 15.1/13.8dB before, 21.1/13 after
Line attenuation 35.5/19dB before, 34.5/18.6 after

Glad to hear that a NTE5 etc. was fitted satisfactorily

It does seem that the downstream sync is set at 283Kbps despite the significant change in downstream SNRM from 15dB to 21dB. I reckon it would be a good idea to contact support and request an investigation into the cause of the slow sync speed. Home wiring is now good, router is good so must be something restricting the sync speed beyond the premises.

so is this data from the test socket ? is the extension wiring now connected via the faceplate of the NTE5 ?

Looks like the line has been banded on download, as stated by 4m2. This will not change unless line is reset.
http://speedtest.btwholesale.com/

do test on above link, then "further diagnostics" which will appear at bottom.
if anything like mine, will show maximum speed for line is 283K. Unfortunately I had to change to another ISP to resolve ( not BT ). Now at 11M

Yes, stats are direct from the new incoming socket. In fact it may not be NTE5, BT man fitted what I think is a new model containing inbuilt filter, BB line goes into top half of faceplate and phone line into lower. There is no extension now, just a cordless base station plugged into incoming socket though I tried disconnecting this just in case. To clarify, we now have new cable from the underground, through the wall direct into the new socket, no extension or anything else connected, just the base station and the BB line to router.

BT speedtester produces 0.1Mbps but connection is too slow to do anything else. TBB speed tester agrees with this result. Now I know the HH and cables are OK I'll go back to my friends' house tomorrow, reconnect it for a couple of hours, then call support if it does not improve. It's a 28-mile round trip or I would take it back tonight. Thanks again for your advice.

In reply to a post by Malwaremike:

In fact it may not be NTE5, BT man fitted what I think is a new model containing inbuilt filter, BB line goes into top half of faceplate and phone line into lower.

Yes, it is an NTE5 assembly. The NTE5 is really the part normally fixed to the wall. The faceplate with a phone socket is a normal NTE5A, the two together comprising what we usually call an NTE5.

For use in lofts an under-stair cupboards and so on there is an NTE5B that can be used instead of the NTE5A. It's just a plastic cover to keep dust and bugs out.

He has fitted the latest Openreach interstitial filter plate in between the NTE5 and the NTE5A, as per an FTTC connection. The older Openreach filtered faceplate is no longer provided.

The 283kbps downstream sync looks very much like banding has been applied, so you need support to remove it. Preferably do a complete new 10-day "training period".

Thanks Bob, I understand now. Engineer Tom said he would fit the latest gear so that my friends could get Infinity if they want it; really nice man who was very patient as the husband has become confused and took considerable trouble to see them happy with the phone.
I'm on my way over to replace the HH now, hopefully will get the BB sorted too.

He sounds like an "old school" BT Tech - the way they were always trained. I hope they kept him happy with tea and biccies!

Yes indeed MHC, he was taken into the lounge and properly looked after! I had a 30-minute call with support this morning and within the hour the line state went from 283kb to 11,400kb and TBB tester is quoting 9.7Mbps. The Indian tech wanted to call tomorrow to check the line but was most understanding when I explained my elderly friend might be confused, so has agreed to call my mobile instead.

My friends are delighted and we are all very impressed with BT service. I am grateful for the understanding shown by BT staff in this difficult situation and award them five stars. Thanks again to this forum for setting me on the right path, as always

LAST WORD: As promised, the call centre supervisor called the following day to confirm that the BB was up to speed and the customer was happy. And BT has confirmed that there will be no charge for their work as it involved their incoming line. My friends are delighted and we are all greatly impressed; all in the next working day, BT sets a new standard for customer service.