I'm very curious about this as well - same goes for our place except it's Bell Canada's lines that are crossing our yard. The junction box or whatever it's called is smack-dab in the middle of my backyard, and when we moved in it fed our place as well as each of our neighbors.
I haven't used any of Bell's services for over a decade, so the first thing I did was cut down the cable coming into our house - but we still have our neighbor's on each side of us feeding from that junction box so we have TWO wires about 10 feet off the ground crossing our yard.
Bell came one year to do "maintenance" on the junction box, and required access to our backyard. I complained that we don't even use Bell, so why are we being inconvenienced by both the wires and their "maintenance" but the workers just said to call Bell Canada to get it "fixed" but whenever I call Bell and tell them I'm not a customer they quickly lose interest in wanting to help me.
I don't want to just cut the wires since I like my neighbors and don't want to start a fight - I just want Bell to either bury them or set it up so that the wires don't cross MY yard!!