Google on Wednesday added another wireless carrier to its Project Fi mobile virtual network operator (MVNO) initiative, U.S. Cellular.

As the nation's fifth largest wireless provider, U.S. Cellular offers service in 23 states with 4G LTE coverage blanketing more than 99 percent of its urban and rural subscribers. The carrier joins T-Mobile and Sprint, the third and fourth largest wireless providers, respectively, as Project Fi partners.

Project Fi, as you may know, was launched on an invite-only basis in April of 2015. Google's branded wireless product now relies on cell service from a trio of major wireless providers in addition to millions of free, open Wi-Fi hotspots to serve customers. Project Fi automatically selects the best network at any given time down to the city block to provide a seamless consumer-facing experience.

What truly makes Project Fi unique is its pricing structure. Google charges a flat fee of $20 per month for unlimited talk and text plus $10 per 1GB of data as needed. At the end of each month, unused data will be credited back to your account meaning you only really pay for what you use.

The invite-only restriction was removed this past March but the one major shortcoming that remains is the fact that Project Fi is only compatible with Google's own Nexus 6P, Nexus 5X and Nexus 6 smartphones.

U.S. Cellular coverage will be automatically rolling out to customers over the coming weeks, we're told.

Lead image via Droid Life