Google has added a third cellular network to Project Fi. US Cellular, the fifth-largest carrier in the country, will be available to Project Fi customers in the coming weeks, according to Google.

Project Fi was announced in April of last year, and it offers a few twists on the way wireless carriers traditionally work. For one, it employs multiple different cell networks — Project Fi phones switch between T-Mobile, Sprint, and Wi-Fi networks depending on which connection is strongest at any given moment.

US Cellular will give some Fi users a boost in coverage

Google also offers a much more customer-friendly payment plan with Fi. Project Fi starts at $20 a month for all the basics (like talk, text, Wi-Fi tethering, and international coverage), and then data is sold separately at a price of $10 per GB. The benefit of this model is that Google credits customers for the data they don't use, so if you pay $40 for 4GB and only use 3GB, the company will give back that $10 difference. The only "catch" is there are only three compatible phones at the moment: the Nexus 6, Nexus 6P, and the Nexus 5X.

Adding US Cellular should help bolster Project Fi's LTE coverage, which was previously focused on big cities or metropolitan areas (especially New York, Los Angeles, Chicago, and San Francisco). According to Google, US Cellular offers 4G LTE coverage for more than 99 percent of its subscribers, which are scattered across 23 states. The biggest gains from this, judging from US Cellular's map, appear to be in parts of Oregon, Oklahoma, Nebraska, West Virginia, Texas, and Maine: