Dean Bubley: Cellular-over-cellular?

Dean Bubley posts a theory of his at the Disruptive Wireless blog. Bubley writes that "UMA/GAN is intended to offer GSM services over a "generic" IP connection." He then states that it is usually implied the type of IP connection will be "WiFi from a dual-mode phone, (linked back via ADSL or cable broadband)" or "using fixed-line VoIP telephones hooked into a cellular core network."

Bubley wonders whether there might beanother type of IP "pipe" such as "a cellular one, ideally another carrier's." He asks "How about GSM-over-3rd-party-WCDMA? Or even more entertainingly, GSM-over-3rd-Party-EVDO?" Bubley concludes with:

I haven't even begun to think about the business models here, or the practical difficulties in implementing this, but given that there are a growing number of GSM/CDMA dual-mode devices, presumably it's only a matter of time before somebody tries something cute with them....