House alarm splitting the download speed?


Standard Member
We wonder if anybody on the AV forum has come across this scenario/problem before and if anyone has any solutions?

We have been suffering from low download speeds on our BT Broadband service about 8 mb download. All our neighbours around us achieve between 39-44 mb.

All checks have been done externally as a process of elimination and all is fine.

The Openreach engineer arrived and decided the problem was due to “star wiring” on the junction box in the loft (where the telephone wire enters the property) this is a CAT 5. He disconnected all the superfluous wires (including the wire to the burglar alarm) – the speed then increased to 39mb download.

When the burglar alarm wire was then re-connected the speed went back down to about 12mb. The problem we therefore have is that one of the wires leading from the junction box is the house burglar alarm wire.

Our electrician informed me that Openreach can may be able fit a filter to the junction box to solve this problem.

BT however “have never heard of a filter being fitted” for this problem, and the problem lies with the alarm company.

In turn the alarm company deny the problem lies with them and is suggesting BT/Openreach should be able to fix it.

So we are at stalemate.

Any help/advice/suggestions?

Kind Regards,


Distinguished Member
Openreach are only responsible upto the Mastersocket. The internal wiring and devices connected to it are your responsibility. It’s down to you or the alarm Co. to sort out the problems that their equipment is causing.


Active Member
I don’t know what alarm you have, however my parents had to get a filter fitted to the phone line for their ADT alarm? In effect it’s the same as any other telephone device, requiring an ADSL filter.


Standard Member
mushii - Thank You - I can understand your logic and acknowledge your clearly high level of experience and technical knowledge.

Much appreciated.

I will go back to the alarm company - it is a local supplier with their own system.

I will report back.



Distinguished Member
Pretty much anything connected to a phone line that has a DSL service, that isn't a DSL modem, will require to pass through a filter.


Distinguished Member
I'm quite surprised that Openreach didn't just re-wire the master socket and extensions so that everything other than the router was wired off the filtered output on the master socket. They did this at our home when we originally had an ISDN line fitted - and then swapped over to 512K broadband all those years ago!!

They split the wiring so that 1 pair was the "input" to the master socket and a 2nd pair was then wired from the filtered output as extensions around the house, with a 3rd pair running from the unfiltered socket to the router.


Distinguished Member
AFAIK all they will do now is disconnect any connections, post the MS that are causing problems if it is a fault call-out. Anything else is often chargeable. Gone are the days when you got service 'for free'.
Being fair every Openreach Engineer that has been to my properties has been great, whereas the 'clown squad' that arrived to sort out some problems for Talk Talk (contracted out telecoms engineers) were a whole different ball game. Wires left un-clipped, faceplates not put on properly, bits of wire left everywhere, cables that were clipped were done with a cable stapler (way too tight) crushing the cable completely and to add insult to injury, they swapped out a modem, without telling me and left with nothing working, saying it was all fixed from their end. There was nothing wrong with the internal cabling or the Modem, it was water ingress into the old BT external JB (which they never checked). Finally got an Openreach engineer to come out and replace it - 30 minutes, job done. No more problems.


Well-known Member
whereas the 'clown squad' that arrived to sort out some problems for Talk Talk (contracted out telecoms engineers)
Don't TalkTalk just use BT lines like nearly everyone else? Assuming that's the case weren't the 'clown squad' subbed by Openreach?


Distinguished Member
Yes they are BT lines, but in my experience (I cannot vouch for others), when you report a fault to Talk Talk, they send out their own or sub-contracted engineers. I have never had Openreach engineers out with Talk Talk. The 'engineers' that came to the premises were sent by Talk Talk because they confirmed the company that they were sending (via email) and they had Talk Talk modems on their van (that they replaced without asking).
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Distinguished Member
My mother had a new line provisioned for Sky the other week. Openreach had to come round, as the house had been empty for 18 months and the line had been connected to Diamond Cable (Now Virgin) and not the BT line.

The master socket was in an inconvenient position in a hallway with no power socket, so we asked if he could move it to behind the TV. This was on the same outside wall as the overhead line, so was probably easier for him to do. His reply was "Well if the cable has become damaged..." 5 minutes, a cup of tea and come wire cutters later and indeed, the line into the house appeared to have been cut at some stage and was unusable... New MS fitted behind TV :)


Active Member
Just done a job for a neighbour where open reach had fitted a master socket on a window sill through the side of the window well away from power and router position

I moved the master socket, I know you are not supposed to , but with my de Walt drill took a few minutes to drill through the Yorkshire stone and fit it where they wanted .

the gel joiner boxes we have , actually say open reach on them . We didn’t ask for that they just came with it written on them








Standard Member
Filter has now been fitted - and the speed has increased to 33mb not the 39mb as promised by BT - but it is a vast improvement.We are discussing with the alarm company the call out fee as I think the filter should be fitted as standard.

One other question - the Open Reach engineer informs us that if we require a BT box then it will have to be connected to the router via an Ethernet cable,is this the case? - the box would be about 30 ft from the router so not really practical.


Distinguished Member
I am not sure what a 'BT Box' is so its hard to comment.
Yes a microfilter or filtered faceplate should have been fitted as standard, it is very very basic alarm installation 101. I would be more concerned that they had not done it in the first place and that is not part of their standard installation. I would also be asking the question if these are the people that you wish to trust your home security to? I certainly would not let them near an install or property of mine.


Standard Member
Thank You.

I am sorry I should have been clearer - I mean a BT box to watch BT televison on my big screen as opposed to my iPad - they are offering a deal for an extra £2 per month.I will check with BT re the ethernet cable.

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