In reply to a post by Shadoogie:

Jan 19th overnight the phone line went dead - by morning it was running again and from then on this whistle/oscillation has existed.
BT say that nothing would have happened overnight and seem unable to track any line incidents that night.

Is any of the phone line overhead and possibly running near trees?

Panasonic dect phones perchance ?

In reply to a post by RobertoS:

I think what should have been asked was if you used the same power supply for the three DECT units, or the power supply that came with each. If you just used the one then that could be the problem.

Also is the DECT base connected at the master or at an extension?

Thanks -

to re-iterate - only one DECT base is used - I have three available so I can test the issue.
The problem exists with all three DECT bases.
The power supply used is the one supplied with each DECT base
The Master socket and the test socket behind it have been used as well as various sockets in the house.
All exhibit the same issue no matter what.
Two of the DECT bases are BT brand - 8500 and 3760 the third is a Response technology company item.

In reply to a post by Michael_Chare:

In reply to a post by Shadoogie:

Jan 19th overnight the phone line went dead - by morning it was running again and from then on this whistle/oscillation has existed.
BT say that nothing would have happened overnight and seem unable to track any line incidents that night.

Is any of the phone line overhead and possibly running near trees?

Phone lines underground but complicated.
I am in a retirement village.
BT line comes into the main centre - is then cabled to a communications centre and then on into a block of 4 flats. And to make matters worse a third party cable firm is responsible for the internal wiring.

Both BT and the third party firm have checked cabling hey are responsible for and declared it faultless!

Re-Explanation Of The Issue and Tests Carried out

Hi folks thanks for all the input so far � thought I would summarise the problem with all the information teased out so far.

The property is a two bedroom flat/apartment in a retirement �village� with six phone sockets �star wired� from the incoming line which has an Openreach master socket on it.

Cables are all underground in conduits.

Important � there was absolutely no issue at all here for 12 months, then one night the line was dead overnight and was back in service next day. That is when this issue began.

BT cable comes into the �Main House� basement and from there through a multicore cable it runs to a small communications building. From that building it runs through conduits to the flat.
There are multiple points of punch down cable connections along the route.

To complicate matters, BT are responsible for part of the cable run and a third party cable company for the cabling on site. Both have had engineers here to check the line and both can find no fault.

I use just one DECT system � a BT 8500 with four handsets.
To rule its potential failure out, I purchased a BT 3560 single handset system to use for testing.
I also have a Response Ltd DECT 2 handset system.

I have used each system in turn one at a time � with its own power supply to test for the fault.

I have tested on various sockets and most importantly on the TEST socket behind the Openreach Master socket unit.

The fault exists with all of them, albeit perhaps a little quieter on one compared to another.

]The fault:-

Connected with an ADSL filter the whistle/oscillation exists at both ends of any telephone call.
Connected without an ADSL filter all is well � no problem.
Broadband BT Hub5 can be connected or not it makes no difference.
A filter is needed to control the ADSL signal hiss and double the speed of the connection.
I have tried four filters � two at the more expensive end and recommended and two cheaper ones.

That�s it.

Any ideas at all?

And thanks for the interest so far.

Have you tried changing the wirless channel on the homehub?

In reply to a post by Shadoogie:

... with six phone sockets �star wired� from the incoming line which has an Openreach master socket on it.

Star wired from the back of the faceplate, or star-wired before the incoming line reaches the master socket?

If you connect both a wired phone and a DECT phone can you hear the whistle using the wired phone, and does it make any difference whether the DECT phone is on or off hook?

What happens if you remove the front of the master socket, but leave the phones as above still plugged in. Can you hear any whistle if the DECT phone is off hook?

PS Google found this.

Edited by Michael_Chare (Sun 05-Mar-17 00:02:24)

In reply to a post by BatBoy:

Have you tried changing the wirless channel on the homehub?

The problem exists whether the hub is connected or not - on or off

In reply to a post by RobertoS:

In reply to a post by Shadoogie:

... with six phone sockets �star wired� from the incoming line which has an Openreach master socket on it.

Star wired from the back of the faceplate, or star-wired before the incoming line reaches the master socket?

Star wired after the backplate