Hi - I am new to the community and have a problem that I think you have the background to advise upon.
I had a new Plusnet telephone line installed about 6 months ago along with fibre broadband. Up until then I was a Virgin cable customer and noticed that the BT lines telephone receiver volume was lower than Virgins. I tried a few different corded phones which all gave similar results. I had an Openreach engineer call to conduct line tests (I have experienced no problems with the broadband) which all passed OK.
I am a retired radio engineer and have used an oscilloscope to check various levels on the line but without access to the neccessary standards have concluded that it is something that I may just have to live with.
While monitoring the line however I discovered that about every 30 minutes the line appears to be becoming looped with the 50 volts DC dropping down to around 8 or 9 volts for a period of approximately two or three seconds during which dial tone is present on the line. To clarify this is occuring when all my telephone is on hook.
In your opinion is there a reason why this is happening? For instance is there any equipment at the exchange that might be causing this? At first I considered that it might have been a cable fault (intermittently shorting) but the regularity of the timing (every 30 minutes) makes me suspect the cause is otherwise. Sometimes the line loops more than once during a 30 minute event with a second (2 to 3 second) loop occuring 2 or 3 minutes later.
This also appears to be happen during a call where a click can be heard followed by a couple of seconds of slight loss of audio volume and an increase in distortion which then ceases with another audible click.
As the cable drop to the house is new and this happens using just the test socket (all extensions disconnected) I am fairly certain the fault must originate at the exchange or maybe from a street box?
Kind Regards
Richard
