When I hooked up to DISH, I was told there would be an extra fee to hook up DISH if there was no landline in the house. I believe the connection to the landline is also a security issue for DISH.  They use this to make sure the equipment is still where it is supposed to be. I had asked about turning off the power when I am not around.  The installer told me not to do that; if that power source is disconnected, DISH would start inquiring as to possible theft of equipment.  As least that is my understanding.

Several years ago, I dropped the long distance from my landline.  I can receive all calls coming in, but I can make only local calls going out.  (Okay with me - I use my cell for all long-distance calls.).  My broadband connects thru my landline, so I was not willing to drop it completely.  Overall, it's been a satisfactory compromise for me.