Two notes against ISP billing, not all Android devices are or will be cell phones provided by a carrier, and when doing ISP billing, as a developer you tend to

Two notes against ISP billing, not all Android devices are or will be cell phones provided by a carrier, and when doing ISP billing, as a developer you tend to get paid 3-9 months out from when the customer bought the product because of the multiple stages of financial transfers. (Seen this with BREW previously)