Analysis of an unofficial Nexus 6 firmware image has shed quite a bit of light on Google’s upcoming wireless service, codenamed Project Fi. Of particular interest is an application called Tycho.apk which is believed to be the hub for MVNO-related activity on Android phones.

Code indicates that Google could be planning to charge customers for data on a per-gigabyte basis. If a user buys too much data in a given month, any remaining data will be refunded to the user. Conversely, if a user runs out of data, more can be purchased at the same per-gigabyte price.

Calling and texting within the US will be included in the core package; international communications are expected to incur a small fee. Shared data and support for multiple lines under a single account are possible and there’s also evidence of data-only plans for devices like tablets.

The app will allow customers to pay bills, manage usage, adjust plan details and even activate new service and request a number change without having to contact Google. Switching between phones also appears to be possible without having to change SIM cards.

Other snippets from the lengthy analysis include the ability for users to port their Google Voice number to the service and even finance the Nexus 6. That latter bit is interesting as earlier rumors have suggested Google’s wireless service would only be available to Nexus 6 users. The latest findings neither confirm nor deny that rumor.

As with most Google products, the company is planning to track call history and use that data for targeted ads. The good news, however, is that it appears as though Google will be open and up-front about this practice and allow users to opt-out from the get-go.

Still no word yet on when Google aims to launch the service but with its I/O conference just around the corner, we’ll likely hear more on the subject at that time (if not sooner).