ZayPay offers SMS and phonecall payments in 44 countries. They have an easy-to-use API. You could make a bitcoin selling service with a simple interface:
I have thought about setting up a service like that and am still toying with the idea. I would, however, like to know more about what happens in case of fraud and Zaypay doesn't say much about that on their website. I haven't mailed them yet. Looking at the numerous attempts of fraud that Coinpal has to deal with, I wouldn't want to be left sitting on phone bills that won't actually be paid.
I also looked at Zong (www.zong.com) which provides similar services and from what I remember reading on their website would guarantee a payment to you once it passed their fraud control. That would be a hassle free way of doing things and simply letting Zong worry about fraud attempts. Unfortunately they didn't want anything to do with Bitcoin. A salesperson at Zong told me that their carriers won't allow anything where you can "cash out" later. So selling virtual currencies is fine, but only if the only thing you can do with them is spend them on some stuff (like virtual game addons or whatever). If there is an option to change them back to "real" currencies, then that would be against their agreement with the carriers. Since then I haven't looked further into the whole "buy Bitcoins with your phone" idea.
Since Zong claimed, that it's the carriers who wouldn't allow this type of stuff on their network, other providers like Zaypay should theoretically have the same problem. But maybe they have different agreements or simply don't care as much.
Con: Half of the end customer SMS fee goes to the telecom operator.
