Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. XMX (or just X) Channel 2 was a commercial-free, satellite radio station on Sirius XM Radio, formerly XM Satellite Radio. Originally used to remind subscribers of overdue payments, the channel changed to a music format on August 1, 2007 and featured popular exclusive XM music programming played all day, every day. XMX was discontinued on November 12, 2008, as part of the merger of the SIRIUS and XM channel lineups. A satellite radio or subscription radio (SR) is a digital radio signal that is broadcast by a communications satellite, which covers a much wider geographical range than terrestrial radio signals. Satellite radio offers a meaningful alternative to ground-based radio services in some countries, notably the United States. Mobile services, such as Sirius, XM, and Worldspace, allow listeners to roam across an entire continent, listening to the same audio programming anywhere they go.