HELP CENTER 
Does on-demand playback on the SirusXM App consume mobile data?
Does on-demand playback on the SirusXM App consume mobile data?

Downloaded on-demand shows are stored locally on your mobile device. While the download process consumes data, playback of downloaded content does not. You can even play downloaded content in airplane mode.

However, when the cellular network is turned on, the background operations of the app (such as channel-list updates) are ongoing and will use mobile data. We recommend turning the cellular network off in your device’s settings before listening to on-demand downloads offline.