Google added mobile operator 3 as a partner to its MVNO service Project Fi, with the move giving users a speed boost in select markets outside the US.

In a blog post, Google said the addition of 3 will give subscribers of Project Fi access to speeds 10-20X faster than before, and there will be no extra fees for using data internationally, with the same $10GB fee applicable as it in its home market.

These speed bumps will be available where 3 operates; in the UK, Austria, Denmark, Hong Kong, Ireland, Italy and Sweden.

The service has always been available abroad and is now accessible in more than 135 destinations, but reportedly delivered speeds at 3G rates or slower.

The partnership with 3 comes after Google expanded coverage of the service in the US in June, adding the country’s fifth largest operator, US Cellular, to its initial partners T-Mobile US and Sprint.

And in March Project Fi opened up its consumer base, which launched more than a year ago, to anyone in the US, after restricting it to a selection-only basis before.

Project Fi works by allowing users to switch between Wi-Fi hotspots and the LTE networks of Google’s operator partners, depending on which is fastest at a particular location.

Google has always been somewhat secretive over the technology used in Project Fi, as well as user takeup statistics.

The company today also launched a promotion offering $150 off the compatible Nexus 6P device for the next week when activated with Project Fi.