Not outside the U.S. and Canada there isn't. (at least not for the SMS wallet capability)
sending SMS is easy but then i would have to take a fee from the sender because sending SMS isnt free! do you think SMS is really needed?
Do you see any pins on the map not in U.S. and Canada?
(this map marks locations for a different metric but it was the only related visual I could easily find)
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http://world.bymap.org/MobilePhones.htmlSo yes, there are many (read hundreds of millions, or billions even someday) of potential bitcoin users where only a feature phone with SMS / text messaging is used.
The challenge though is a method that is secure (from spoofed SMS text messages though).