How to stop noise on a telephone line?

Question

The line goes all crackly when I wire in an extension socket to the master socket

Do I need a new master socket

I am using new cable and a new extension socket both from bt

Also bt have tested the line and found no faults

Please please please help me

Thanks In Advance

Answer 1

if the line is not noisy before you connect the extension but is noisy when you do, it sounds like the connections have not quite made causing a high resistance fault. Check the connections have 'made' properly.