This past week at Mobile World Congress, Google executive Sundar Pichai confirmed that the company was working on a wireless service that would look to leverage WiFi and new technology that could seamlessly transfer you between different carriers’ networks to ensure quality service. There aren’t many early official details at this time, though rumors have suggested Sprint and T-Mobile will be on board in the early going.

The Wall Street Journal says they’ve heard word that there will be one big caveat for wanting to try this service out, though: you’ll need to own a Nexus 6 if you want to play ball. That may seem like a foul stipulation at first, but it makes total sense.

Google isn’t simply becoming an MVNO ala the likes of Republic Wireless or Straight Talk. They’re creating and testing an entirely new cellular technology that simultaneously leverages WiFi and any number of network signals between any number of carriers to help deliver the best call and data experiences.

It’s an ambitious project, but the only way they’re going to be able to accurately judge results is by keeping variables at an absolute minimum. It’ll be important for Google to be able to control the usage environment as tightly as they can in order to ensure everything works as it should. If that means they can only approve one phone for this experiment then that’s what we’ll have to accept. We’re almost 100% certain we’ll hear more about this venture at Google IO, with the Wall Street Journal suggesting it’ll be ready to go “in the coming weeks.”