The public launch of Project Fi marked the end of a 10-month, invitation-only test phase and comes as the Internet giant's first foray in being a mobile phone service provider.
"We're excited to be exiting our invitation-only mode and opening up Project Fi so that people across the US can now sign up for service without having to wait in-line for an invite," product manager Simon Arscott said in a blog post.
"With Project Fi, we deliver fast wireless service with the flexibility to use it where you want even internationally and a monthly bill that's simple and easy to understand."
Project Fi is only available for Nexus 6P, Nexus 5X, and Nexus 6 smartphones from Google and work with a special SIM card that supports connections to multiple cellular networks.
Project Fi enabled smartphones can link to one of two 4G LTE networks or to Wi-Fi, automatically selecting optimal connections and switching from one to another without interrupting service, according to Google.
"As you go about your day, Project Fi automatically connects you to more than a million free, open Wi-Fi hotspots we've verified as fast and reliable," Google said in a blog post.
"Once you're connected, we help secure your data through encryption."
Basic Project Fi plans cost $20 monthly for unlimited domestic voice calls as well as unlimited domestic and international text messaging. Fi boasts cellular coverage in more than 120 countries.
Data service costs $10 per gigabyte, with people only charged for what they use.
Google promoted Fi service with discounted prices on Nexus 5X smartphones.
The move by Google is seen as a way to lure consumers away from Apple and promote Google-branded Android phones with an a low-cost mobile plan.
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