I see Aeria has implemented the Pay by cell phone but Has not implemented a Pay by phone type of system yet.
NCSofts DungeonRunners is a free MMORPG with the option to buy membership to access better things and exclusive servers and they use Surfpin Payment as a payment option.
This could easily be implemented to Aeria's style of AP purchase (IE. 3 Different 900 numbers with 10 25 and 50 dollar purchases for example)
Surfpin charges a small fee and by using this system has the potential to increase revenue by 10-25%.Because it opens options to people around the world that otherwise would not be able to access Aeria's AP system.
The Website is http://www.surfpin.com/
Oh and Surfpin also allows for cell phone payments as well