I just hope that the poor of the world don't end up with a $180 phone bill like I have to deal with in order to have mobile web access. Sadly, in some countries that would be almost 6 months' income.
The average Indian user is worth about 0.03c to a network, with no contracts or lockins, and people frequently switch network to network depending on deals.
In fact, in order to avoid fees, a new system has appeared. Calling, letting it ring once, and hanging up. It doesn't cost but it DOES ping the other person.
These call-backs are becoming so pervasive that businesses let people call-back and the business calls them back, at their own expensive, to offer whatever service. Some Indian apps are also incorporating the call-back system into their communication structure.
Don't think that just because we have dumb contracts and bills that the developing world will as well.
Where there's money to made, a way will be found.
EDIT: I do this by using T-Mobile PAYG and buying their 6 month Internet booster for £20, twice a year. I've managed to convince all my regular contacts to use Kik Messenger instead of SMS, so I don't have to pay for SMS. I very rarely make phone calls, but I have VOIP with localphone.com when I have to.
I'm a localphone customer here as I am not in the UK. :/