There is another approach. To my knowledge, it has never been used anywhere in the world.
One monopoly could own, operate, and maintain the poles, wires and fibers. They would be a public utility and be answerable to the public service commission for tarrifs and meeting reliability and availabilty requirements. But they would not provide any consumer service at all. Their customers would be the electric power and communications companies that rent use of the facilities. Perhaps even natural gas and water distribution pipes could be included in the bundle.
It is already true that power and communications utilities outsource a lot of the line construction, operation, and maintenance of distribution to outside contractors, so the change might not be a dramatic as it sounds. It would be primarily a legal change to make these contractors public utilities, with the rights and obligations that go along with their role.
Please correct me if you know of some place where this approach has been applied.