The Nokia 105, a voice-and-text feature phone, is priced at $20. It runs on Nokia's Symbian Series 30 OS and offers support for text message, an alarm clock, an FM radio, reminders, and a few simple games, like Sudoku. But it can't surf the web.
Guess I shouldn't be putting questions in here that I don't have an answer for, but I suppose this really won't quite "substitute" for a smartphone since I doubt you could really watch video very well on it, I mean how much GPU can you afford in the BOM for a $25 device? Without enough processing power you'd use even MORE BW if you had to almost "stream pixels". But I don't really know how much low-end GPUs sell for in huge quantites, maybe someone else on here knows. (Or maybe you HAVE to be able to support video in order to run the ads you need to monetize the sale of the device?) Definitely some issues that need to be looked at anyway, don't think this article answered all the relevant questions yet.
I think this is not cheap alternative of iPhone or Android phone, instead it is feature phone with touch screen. You can make phone call, web access, e-mail, messaging, some extra features (caldner/scheduler, camera, etc), that's all. You won't have fancy voice-recognition AI, you won't have millions of online Apps, but do you really need them?
My primary question is if it can achieve "good enough" quality in $25 price tag. If LCD visibility, touch screen precision / sensitivity, battery life is below minimum expectation, it will never take off. In my opinion there will certainly oppotunity for simple low-cost phone, but $25 retail price tag would be going too far.