Most of the poles that have metal steps on the sides of them are ones that date at least as far back as the 1950's.
Exceptions: I've seen a couple of poles dated as recent as 1974 that have them. One of them is located in the beginning of Main Street in Montague Center, near a bridge; the other is located on Turners Falls Road in Turners Falls.
Some more exceptions: two telephone company poles in Turners Falls — one only as far back as 1968, the other from 1971 — also have climbing steps.
I remember years ago that a 1969 pole in my area had climbing steps at one time. Climbing step holes that remain in the pole proves that my memory serves me correctly.
More exceptions to the rule: There are occasionally some really old poles that I've seen that don't have climbing steps.
These steps are "L" shaped, with the end of them pointing upward.
I have also seen some climbing steps that appear to have a rounded head, making them look more like giant nails.
I saw unusual climbing steps on one pole in Deerfield. They looked like the "L" ones, only the otherwise shorter part was much longer than usual. An older pole in Amherst has climbing steps with this unusual appearance as well. I believe I may have also seen such steps on a few poles in Bernardston or Greenfield.