SPH -

That particular system was a very, very early computerized PBX. They were trying to keep foreign data/static/noise out of the system. It worked.

STP is prevalent in Europe. And it's our (America's) fault. One of the scenarios for Nuclear war calls for exploding a small nuclear device in the atmosphere above the enemy's territory, with the aim of disrupting communications.

We anticipated war with the USSR, with conflict beginning over the German Plains. When we rebuilt the West German Phone system after WWII we insisted that all wiring be shielded to protect communications from nuclear interference.

The idea of shielding comm wire became standardized across Europe.

If you don't have noise or RF - don't bother. I would think that it's probably overkill.

Most OSP cable coming in from the street is shielded. So you usually have shielded and non-shielded on the same run anyway. (A line would be shielded from the CO to the premise and then be unshielded inside the customers premise).

Sam

"Where are we going and why are we in this hand basket?"