Phone interference

[bravheart]

Ok any ideas on how to sort.

Mums got a care alarm and a broadband router plugged into the phone line both working fine. Plugging a cordless phone into the same line causes interference noises in the phone when making a call making it unusable. We thought the cordless phone was knackered so bought new ones and got the same problem. Moved all the boxes to different rooms and still the same, unplugging either of the other two boxes cures it as far as I can make out, help lines not very helpful because their equipment works fine on it's own.
Any ideas, what else could I try?
M.

 

[J B]

Presumably (?) you have either a filtered faceplate or a filtered adapter for the phone - maybe that is faulty?
I have heard folks say that they put two in series to help, would that be an idea?

 

[bravheart]

Presumably (?) you have either a filtered faceplate or a filtered adapter for the phone - maybe that is faulty?
I have heard folks say that they put two in series to help, would that be an idea?

Think this may have sorted it, had someone out at it today, noisy line apparently, filters on every plug and seems bearable atm. Fingers crossed, thanks @J B