Google announced today that its Project Fi wireless network, now rebranded to Google Fi, will be available for iPhones and the majority of Android devices. That’s supposed to open up a lot more phones to Google Fi’s unique features, such as flat rate data billing; unlimited international roaming; and the ability to switch between multiple networks, like T-Mobile, Sprint, and US Cellular, for better service. However, if you’re planning to use your iPhone on Fi, there are quite a few caveats to be aware of.

Though Fi SIMs have unofficially worked on non-Fi phones (including iPhones) before with some limited functionality, Google is now supporting iPhones directly. You can go through the Google Fi site here and check if your phone is compatible, but to save you some time, you should know that iPhones won’t be able to make calls or text over Wi-Fi, use visual voicemail, or be used as data hotspots outside the US at all. They also won’t be able to take advantage of Fi’s unique network-switching features. Google Fi flat-out won’t work on the iPhone 5, 5C, or older.

You’re fine if you have an iPhone 5S, 6, SE or newer, provided that it has been carrier unlocked. Though if you have a newer iPhone, this shouldn’t matter as much, as new iPhones can use LTE on any American LTE networks. This makes Google Fi’s caveats for iOS all the more disappointing, as it won’t allow carrier switching but will automatically default to T-Mobile’s network for calls, texts, and data. You’ll also have to update your MMS settings to send and receive texts to non-iPhones, but iMessage will work right out of the box. Google also says you might have to update these settings a couple of times a year if they get changed due to an iOS update.

Today’s news is more of an official acknowledgement by Google rather than an announcement of proper support, but Google Fi does have a pretty interesting pricing model that might be cheaper than other carriers, depending on how much data you use. Each phone line is $20, and $10 per gig of data, which caps at $60. With Google Fi, you can receive your voicemails as transcribed texts, and there’s no international roaming fees. If this all sounds good to you and you want to make the switch, there’s a Google Fi iOS app to help new users get set up.