Hey Dave,
You might get insight into whether or not the telephone wire is MSP related or by taking a look at what it's doing higher in the tree.
Forest lookout telephone lines were
very often strung through the trees, and the wires themselves strung through 2"-3" diameter white porcelain "donuts" that were essentially eye-lag bolted into the the trees.
If you look up and see a glass or porcelain insulator on a side pin, try to get a photo of it - I can ID it and give you an era/age estimate.
It's also possible this is just free span wire between insulator supports that became entrapped/entangled in this tree. No clues there.