We need carrier killing hardware and a carrier agnostic data radio tower setup.
The hardware would have an open boot loader ready to take on Android, Ubuntu, Jolla, and any other open sourced ROM available.
The hardware would include the five major HSPA+ bands (850, 900, AWS, 1900, 2100), and LTE bands (4, 17, 13, 7, 3, 25) to cover a majority of the spectrum used by carriers in the Americas, Europe, and the rest of the world.
The hardware would also support a USB dongle for additional carrier data support for carriers who do not provide SIM cards.
Beyond that the hardware will support a protocol for carrier agnostic mobile accounts.
Cell towers would run like WiFi access points, and the mobile device would handle the hand off between towers.
Each tower can even be run by an individual entity if desired, no national or regional carrier system would be needed.
Instead there would be entities that sell data credit to end users.
A mobile device would have an account with a data credit reseller.
The mobile device can scan for access in its area and connect to a tower based on how the user priorities (cost, speed, signal strength...)
The tower would then charge the data credit reseller for the user's usage.
This setup allows for each cell tower to compete for users in an area.
This would allow start-up wireless companies to compete immediately.
Once enough individual towers went up then it would compete with the big carriers and force them to change and join the carrier agnostic system further driving down the price for data for consumers.