I have just replaced our phones, with a set which filters out nuisance
callers, unless they are live callers who can follow a proceedure to
get through.

My new concern is that we sometimes get automated calls from the
electric, gas, flood and water utilities, when they have an issue and
we obviously want these calls to get through - so I need to find out
the numbers they use to ring us from, so I can include them in the list
of accepted numbers.

Has anyone found such a list, or even a proper name for this type of
prerecorded warning phone call?