Mains interference on landline phone

Stoodles

I think that is what I'd call a buzz - I suppose it's a bit subjective.


"Probably because you've stopped all landline telephone communications"
I've been testing whether the noise stops by dialling 58, which results in "the number you have dialled has not been recognised" While that message is playing, I either take the mains jack plug out of the back of the phone, or switch off at the socket.. The buzz stops, but the message carries on playing. Once I reconnect the mains, the buzz restarts.


I've just checked, and I can make a call with the mains unplugged, so I think it must be powering the display and answerphone, not the phone.

Heedtheadvice

As indicated above the problem likely lies with a faulty power supply in the base unit or the supply to it. If it is a DC power supply that is plugged into the base unit then it ought to be marked with it's DC output voltage (such as 12v) and it's output current (such as 1A or 500mA). [Some power supplies just step down the voltage from mains (240V) to a lower voltage and the base units then convert to DC to power the unit and charge the batteries but that is unlikely.]


Do some testing! EDIT: Just seen your response above so you have answered some of this already but left in for completeness


When the power supply is switched off or disconnected can you still use the phone to make calls? If not then you cannot tell if the hum is coming from the power/base unit or the telephone line. Best plugging in an 'old fashioned' analogue phone instead of the Binatone and having a listen. If hum is still present then the line is suspect or interference (see below).
If you cannot hear ANY hum on the analogue phone and the power unit is a DC one (detailed as above) then you can try plugging in another one that has the same connector (polarity marked on a symbol on the unit), identical DC voltage output ans at least the same current (amps or milliamps) output. See if that resolves the problem. If so it can be a very cheap fix!



Note that although mains frequency is 50Hz ( a very low frequency) the process to produce DC from that AC can generate harmonics such as at 100Hz or 200Hz (frequency of very low male voices) and these are both reproduced louder by telephone equipment and are easier to hear than the 50Hz.


Secondly it might be that main powered equipment close by is causing interference especially if their main power cord runs close to your telephone or it's cables. If there is some in the vicinity try separating the cables by a few inches/cm. The equipment can be at you main base unit or at an extension.


Much potential interference by a router (do try the above tests with the router disconnected) is too high a frequency to be audible.


I have noted more than once equipment that is also connected to a telephone line can generate the hum you hear such as a sky box that uses the telephone line but I would put my money on either the PSU or the line being the problem.


You do have a filter fitted? Try changing it too if nothing else sorts the problem.


Best checking the telephone line with the analogue phone (at a test socket if your master socket has one to rule out any other connection you may have or all other extensions/equipment disconnected) before calling in support and testing from your supplier as if the fault is found to be something for which you are responsible there could be a hefty charge!

abssorb

This is a Power Supply Unit for a binatone:

https://www.amazon.co.uk/replacement-Supply-Adapter-binatone-concept/dp/B00FIXOTM4

They can break. Sometimes they stop working altogether and there is no power, sometimes they can break in such a way that they cause a buzz to other electronic devices. In this case your phone's own power supply might be interfering with the phone's handset speakers.