I think this idea deserves more recognition.
A phone is much more accessible and widely available than a computer. There are many, many people for whom they only got a phone.
Even some kind of SMS / gateway / key exchange would be something… being able to send a payment by sms to a gateway server with an unsupported phone to a supported phone, for example, or to a trusted third party who can handle the transaction for us. By rolling passcode perhaps.
That would fantastic, and possibly not too much of a major overhaul needed?
Inspired?
I am working on an open source SMS project that may be capable of providing this capability. However, I am not so familiar with how payment would be handled by text messages.