After confirming that the telephone service to our house still worked (by plugging a telephone straight into the telephone box on the side of the house), Lisa concluded that there must be a wire broken somewhere, and that it must be in the wire between the box and where the line from the phone box branches out to the various telephone connections in the house. That sounds relatively easy to fix until you learn that the telephone wire is literally cast in concrete.

The white wire here is the connection from the telephone box to inside the house. When a previous owner put the decorative rock facing onto the house, they decided to literally embed the wire in the mortar of the wall. The cable connection (black wire) also runs through the wall, but they put a small conduit for it, or possibly someone drilled a hole and installed it.
This annoyance is something we will turn into an opportunity. Lisa has been wanting to run a new set of telephone and cable wiring from the utility connection boxes anyway, so this just means doing it now instead of later. So off to Lowe's we went to buy conduit, a box of wire (she already had a spool of coax cable), and sundry connectors and fittings.

Lisa spent time when weather and her energy permitted digging a hole under the outside of the house. This morning, while I worked at the Day Jobbe, she kitted up in coveralls, gloves, and the N95 respirator (generally proof against paint, dust, and mold), climbed under the house, dug the other side of the hole, and put in the conduit through which she pulled the telephone and cable connections from their spools in the wiring closet on the opposite side of the house. (I helped a little bit by feeding cable/wire down the hole.)
This is not finished, because unfortunately one of the fittings broke during installation, so we'll have to go buy a new fitting. We also need new cartridges for the respirator, because one of the two cartridges broke while she was crawling around under the house. (It's a replaceable part, but you have to find the replacements, and there's been something of a run on these high-grade masks and their replacement parts due to the pandemic.) She also intends to attach the conduit to the wall so it doesn't move around.
The wires are not in conduit under the house, but Lisa will tie them up to an underfloor beam. She may get fit-over-the-wire conduit (rubber conduit with a split down it; you snap it over the wires) to protect the lines as well.
Once we have the remaining parts, Lisa will hook everything together and move the cable and DSL modems into the wiring closet. From there, she'll run lines from a distribution panel to elsewhere in the house. I think it's pretty nifty myself, and I'm sure glad we bought a small used rack panel from Weird Stuff Warehouse (R.I.P.) that Lisa mounted in that closet. When she's done, I will no longer be kicking a bunch of wires under my desk where the existing head end for the cable modem and router are located.