Yes this is industry standard practice. I worked on the official mobile appstore for AT&T Wireless (way back when it was known as Cingular) that handled rington

Yes this is industry standard practice. I worked on the official mobile appstore for AT&T Wireless (way back when it was known as Cingular) that handled ringtones/graphics/apps/games and we had access to that header as well for billing purposes. We used it to track purchase history on that site for recommendations/profiling and also used it for segmenting the mobile UI storefront.