Google's Project Fi mobile service usually requires an invite (and subsequent wait) to get in, but to mark the official release of LG's Nexus 5X, anyone in the United States can get an "instant invite" right here for the next 24 hours. Project Fi works with both of the new Nexus smartphones, so it's definitely in Google's interest to advertise the MVNO service alongside its latest mobile hardware. The Nexus 5X in particular offers a cheaper way into Fi service than last year's Nexus 6 flagship.

Project Fi starts at $20 per month for voice and text, and then charges users $10 for each gigabyte of cellular data they need; you're only charged for the data you actually use, and Google credits back any unused portion. Fi combines the cellular networks of T-Mobile and Sprint, switching between them depending on which has better coverage. The service also makes heavy use of Wi-Fi for calling and data access. Setting up and actually using Project Fi can prove a bit more complicated than it initially seems, though. But if you're willing to ditch your current carrier for Google's service — or give it a tryout — today is your best chance for immediate access.