I have 5 fiber conduits running through my front yard, I watched them plow them in years ago. They connect a local switch to one a couple of miles away. So last spring I was going to replace my mail box post, an old uglt, rusty H beam stuck in the ground about 3 feet deep with a 4" tube post powder coated Kubota orange, and since it's been such a long time since the fiber was installed, I didn't remember just how far from the post they were. I called the phone company, they said call 811. Called 811, they said they only locate gas and electric services, call the phone company. Called the phone company back and explained what 811 said, they said the fiber wasn't theirs, call 811. Called 811 again, they came out and located my gas and electric services which are 100 feet from the mail box post. I went out and asked the 811 guy who I need to contact about the fiber, he said he didn't know.
So I pulled the H beam out with the Kubota and relocated the hole a foot farther back from the road, using a post hole digger. I didn't run into any of the fiber conduits, but I know they are there close.
I never have found out who to contact to locate those fiber runs.