In which case you should get the 'equipment busy' tone not just a
message "Sorry there is a fault". Though that is probably better than it
used to be with GPO telephones where (shortly after STD) trying to phone
from Southampton to Birmingham might be met with a message such as "All
lines to Brighton[1] are busy, please try later"
[1] Or some other place which seems to have no bearing on the call being
attempted.