Further to
Eric's reply, if there are still crackles and other noises present on the line when just a corded telephone (and absolutely nothing else) is connected you should report it to your telephone service provider as a
voice fault, without making any reference to the broadband service.
Regarding the
XNTEs, I have been reliably informed by a serving
Openreach employee (
Black Sheep) that those devices are now no longer installed. If in the course of remedying a fault one is found to be present, they are permitted to disconnect the internals and fit an
NTE/5A within the premises.
Please see the latest revision of
SIN 470, Issue 2.0, April 2012, Section 5.