Its only successful because it is a monopoly, it doesn't give a **** about its customers.
The problem is that a so called pair quality check is probbly done with n electronic, softwre controlled test meter. This will sample then compare, then display the results at that time of sample, they are little help in identifying a 'tapping' fault.
What are BTOpenreach line limits for their poor service to rural customers? A 1600Hz signal into a 1000ohm loop resistance can drop about 10 dB. Does anyone know what are their limits for line to test as good?
Lookup up 'SIN 349' , it contains the technical specification of a (BT/OR) local loop (metallic path facility)