telephone wire needs to be cut back to expose new wire in order for...

[shygirl83]

...phone/internet to work? the black wiring coming in from outside for my telephone socket often needs to be cut back to expose a new wire to enable my phone and internet to work again (once this is done my phone and net will work well without interuption for about 2-3 days but then my phone starts crackling again and my internet plays up so i always need to keep cutting the wire back to make it work) its getting to a point now where the wire has been cut back so much (over a period of 2yrs) thats its very close to the wall (hols it comes through from outrside) so i cant really cut it back any more.. does anyone know what is wrong with the wiring and do i need to change the whole cable from maybe where it is connected outside? how do i do this or should i call an engineer? is that expensive? Thanks