Google extended the coverage of its MVNO service Project Fi with the addition of US Cellular, the country’s fifth largest operator, to its partner list.

US Cellular joins existing partners T-Mobile US and Sprint, and its network will be available automatically to Project Fi customers “over the coming weeks”, said Google in a blog post.

Project Fi, which launched more than a year ago, allows users to seamlessly switch between Wi-Fi hotspots and the LTE networks of Google’s operator partners, depending on which is fastest at a particular location.

In March, Google opened up the service to anyone in the US, after previously restricting it to a selection-only basis.

US Cellular provides mobile services in 23 states in the US, with LTE coverage to more than 99 per cent of its subscribers, said Google, and its addition to Fi “now gives you more coverage and speed, helping you stay connected wherever you are”.

Evan Jacobs, product manager, Project Fi, explained the majority of Project Fi usage occurs in areas where more than one of its partners offers LTE coverage, but connections can be harmed by obstructions from nearby buildings, affecting speed and coverage.

Project Fi is able to analyse speeds from different networks, and predict the fastest network at a location, which he said will further improve with the addition of a new partner.

“By accessing multiple cellular networks, Fi users have a connection 99 per cent of the time, and spend about 95 per cent of cellular time on LTE – which will improve further with the addition of US Cellular,” said Jacobs.