Eigenvector wrote:
I can't find a good solid ruling for this one.

Are phone lines grounded locally at the house?

The configuration at my house has the main phone line coming off the pole,
down to a junction box, where 2 phone lines leave and a single ground wire
connects to the cold water plumbing.

I can't find any definite answers as to whether or not that ground wire is
required, desired, or useless. The intent is on replacing the whole setup
with CAT 5E (seeing how it's just as cheap as CAT 3 or phone cable) and
re-routing the wires, but I don't know if I need to keep the ground wire.
It looks like pretty standard 14 gauge wire, in a grey sheath.
..
Telephone line protection here, here which AFIK follows Bell Canada
(ATT) practice is a 'Protector' mounted where the telephone line enters
the premises. Sometimes mounted outside but often inside the house.
That protector requires a ground.

The telephone company would either have driven their own ground rod or,
as in our case run a grounding wire to the incoming metal electrical
conduit which is grounded by the power company; that ground is also
bonded to metallic water pipe.

The protector (similar ones have been in use since the 1800s) provides
voltage breakdown protection from each side of the telephone pair.
Those are either repairable manually or by replacing small slide in
units; they are essentially small spark gaps that will break down to
ground if voltage exceeds a certain figure. Can't remember what that
voltage is offhand.

Also these days if one is within distance of the server, Internet
service can also be provided via the telephone pair.

The cable TV company have a coax entering the premises and it also has
a grounded protector.