They don't seem to worry too much. Here is a pic of my phone line (in the parcel) after it was fixed but before the contractors replaced the soil. The hole is less than a spade's depth.
http://tinyurl.com/c8jjjy8
Plusnet Value Fibre Pro 80/20 test, ZyXEL NBG4604 , St Ives Cambs EMSTIVE