Appears to be a very interesting project. 
So pay for mobile web access with BTC. 
It appears to have it's own SIM.  I know other countries than the US, has separate SIMS for phone and network. 
So I am assuming this will work in same manner. 
Only difference is getting networks like let's say Verizon or Sprint to accept BTC as form of payment especially with it's volatility is worth.  Then again it depends on usage and what you ring up as charges. 

I look forward to seeing this project in action.