The antenna system has been programmed for either DTV or Dish; Almost all are set to the DTV satellites. There are some great threads throughout this Forum on setting up the system and yet there is a lot of wrong information also.
First - all receivers (like the H24 or HR24 box) are owned by AT&T many are a one time charge lease and no return requirement. A part of what that means is the tuner is registered to an account / location and it's a violation of the agreement and contract for service to change without approval. In other words you can't give it to uncle Vinny so his family has service.
Second - if you activate with AT&T for a boat or RV and you have an active DTV account then it is only an additional receiver charge of $7.
Regarding obtaining a receiver - The receiver and card needs to be obtained through an AT&T authorized retailer. It would be bad for you if you got one through Ebay and tried to register it only to find out AT&T will not accept the S/N or card. I obtained mine through Solid Signal
https://www.solidsignal.com/ who are an authorized DTV retailer and followed their detailed directions; I had no issues other than programming an antenna type in the receiver to one that will work with the KVH antenna. I think I used "Slimline" but it has been around 4 years ago.... There are many possible selections; it simply takes time.
You must first get the receiver and antenna working together and get your system talking to the satellite before you contact AT&T to register. Your TV will get the DTV splash page when it is communicating.
Then contact AT&T to activate the receiver; you will need the number on the card and Serial Number of the receiver so make sure to write those down first when you get the equipment and your account number. AT&T activates the receiver through a signal downloaded through the satellite system; that is why you need to first get things communicating.
AT&T didn't ask where the receiver was located other than we discussed a mobile application - They charge my account only for an additional receiver which is $7.
The down side - your system will not communicate with satellite 103 which in our area is the HD feeds so you will only receive the SD channels but there are a lot of those still.