Voom HD Networks was a suite of 21 original high-definition television channels owned by Rainbow Media, a subsidiary of Cablevision. The channels were produced in high definition with Dolby Digital 5.1 surround sound and were the largest suite of HD channels in the world. As part of a 15-year agreement between Rainbow Media and Dish Network, these channels were available on Dish Network until May 12, 2008, when Dish walked away from the contract just over two years into the deal.