1. Armored Cable
Old phone lines encased with wire are referred to as "Armored Cables".
Previously installed in homes and small business, the armored phone line was manufactured to withstand damage caused by unsuspecting owners & trades people.
As in this picture, the centre of the cable consisted of the phone line as a single pair of copper wires.
These wires were individually wrapped with orange paper to insulate against shorting.
Next, the pair of wires was wrapped with pink paper, again used as an insulator, followed by a lead metal sheath to protect the wires from moisture.
A third layer of paper coated with black bitumen was added to protect the lead sheath from corroding.
Finally a heavy duty wire casing was added to protect the soft lead sheath from damage.
This protection was very effective but no doubt an expensive awkward process to manufacture and join.