cancel
Showing results for 
Search instead for 
Did you mean: 

Noisy phone line when router connected

tich731
Grafter
Posts: 53
Registered: 16-11-2007

Noisy phone line when router connected

My phone line is quiet without the router connected but develops loud crackles/noises when router is powered up and the DSL connects. I have tried a different router with the same result. I have also changed the filter.
I have no other equipment connected to the phone line.
Can anyone suggest a course of action.
Thanks
72 REPLIES
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: Noisy phone line when router connected

Hi tich731,
I've just carried out some testing on your line I've not been able to spot anything remotely. Does the crackling only start once the router is powered up or is it still there when there's just a phone connected?
Chris Pettitt
Cloud Environments Engineer
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Thanks for the quick response.
The noise on the line does not start when the router is powered up but when it is connecting to the DSL line and with the DSL line flashing. (Sorry if I wasn't clear on this)
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Also, the line is quiet when there is only a phone connected.
Superuser
Superuser
Posts: 11,100
Thanks: 2,471
Fixes: 22
Registered: 22-08-2007

Re: Noisy phone line when router connected

Where both routers using the same PSU?
Is the phone DECT or wired?
Is the phone using the same socket / filter as the router?  If separate, both phone and router must be plugged into filters.
Are the two (or more) filters identical?  Have they both been used previously?  Note they could both / all be defective.
I sometimes can hear very faint modem noises on the phone line, but not something matching what you describe.
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Yes, both routers were using the same PSU.
I have tried both a DECT phone and a wired phone into the main socket with the same result.
Phone and router are both plugged into the same filter/socket.
I have substituted a new Belkin filter for 2 other unbranded filters with the same result
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

The noise on the line cannot be heard by the caller.
Superuser
Superuser
Posts: 11,100
Thanks: 2,471
Fixes: 22
Registered: 22-08-2007

Re: Noisy phone line when router connected

When you are using the phone, do you hear any echo or distortion?
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

When using the phone, there is no echo or distortion, just noise and crackle.
Out of curiosity, I have just tried a broadband speed test and found it to be very slow, <1Mb. I used to get close to 6Mb. Is this related?
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Coincidentally, I have just lost connection by the router in the last 2 minutes.
Community Veteran
Posts: 1,611
Thanks: 22
Registered: 29-06-2010

Re: Noisy phone line when router connected

Another possible cause is the RJ11 cable from the router to the filter - have you another one to try?
Community Veteran
Posts: 3,380
Thanks: 2
Registered: 18-01-2013

Re: Noisy phone line when router connected

My initial thoughts were the filter - a failed or failing filter can cause this exact issue but you say you've changed it already. Was it a new (or known working) filter or perhaps another  potentially duff one ?
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Thanks for those suggestions.
I had already tried a different RJ11 cable.
I bought a new Belkin filter to replace the unbranded one.
I have also double filtered the phone.
None of these actions has had any effect.
Do you think that the router disconnection(s) and slow broadband simply coincidental?
Superuser
Superuser
Posts: 11,100
Thanks: 2,471
Fixes: 22
Registered: 22-08-2007

Re: Noisy phone line when router connected

No!
Can you please gather the information requested in the speed issues thread at the top of the broadband forum?
tich731
Grafter
Posts: 53
Registered: 16-11-2007

Re: Noisy phone line when router connected

Results as requested:-
1. Router Stats
                            D/s                U/s
Noise Margin  30.3dB        22.9dB
Speed                1151Kpbs    443Kpbs
Attenuation        40.0dB        20.5dB
2. BT Speedtest
Download        0.79Mbps        Acceptable range  0.4 - 1
                IP Profile  1.01Mbps
Upload              0.24Mbps      Upstream rate IP Profile 0.45Mbps

3. Current Line Speed 1Mb