Could be creosote...probably Penta or CCA would be my guess. Don't see any green tint so my guess is creosote or Penta.
Would have to put this well trained nose to it ( Dad was in the lumber treating business all my life) and I worked at the treatment plants in HS and college. Love the smell of creosote but hated cleaning the treating cylinders.
Actually, they are called both posts and poles depending what part of the country you're in. Everybodys right. Fence pole or fence post was used....sorry, these are not telephone poles even though the treatment method is nearly similar.
Gotta admit, heck of a post to get this many replies.