Additionally, Twilio is the nascent, embryonic form of the first Internet that a
billion people are going to have access to, because Twilio turns every phone
into a smartphone.
So the total potential market for Twillio apps is the amount of mobile phones in circulation which are not smartphones. Will this number not be shrinking in a few years, even if the predominance of non-smartphones in developing countries is causing it to increase on the short term?
For arbitrary businesses reaching out to mass-market clients, it'll be a decade at least before "customer is extremely likely to be carrying true smartphone" will translate to "exploitable assumption". Local businesses do not as a rule write cross-platform phone apps. If you want to be the company that e.g. gets rid of those stupid flashing pager things that restaurants give people waiting for tables, it helps you very little to know that 1/3rd of restaurant customers will be holding an iPhone.
On the other hand, that application is more or less "hello world" with Twilio, and presents a fine customer experience even to people with iPhones.
One might say this would include landlines and to some degree existing phone systems inside companies. Those numbers are probably shrinking some (especially landlines in some areas) but I don't think they'll go away entirely for many moons.
The current hotness is apps, but you generally write a different app per device platform. If you think of smartphones as 'http enabled devices', Twilio is allowing a cross-platform experience.
I don't buy it entirely - much of the benefit of http-enabled devices is the display of information as much as the information itself. Not just 'hi res displays', but any display at all. Information transmittal via twilio is often audio/time based. For the same reason podcasts haven't replaced websites, twilio phone interaction isn't going to replace smartphones, websites or anything else.
BUT... it's a great adjunct tech, and does open up a lot of possibilities for new avenues of information exchange/interaction. One might go so far as to call this a 'blue ocean', assuming you'd read that book and agree with the blue/red categorizations. :)
The market for Twilio is every phone in the world. We also offer SDKs for iOS and Android phones to make and receive calls with Twilio Client. http://www.twilio.com/api/client
