The first invites for Project Fi, Google’s new mobile carrier service, went out this week, but there’s a pretty big catch for anyone who signs up. Screenshots from the signup process shared on Reddit reveal that you’ll lose your Google Voice account and many of the features that come with it.

Project Fi lets you keep your Google Voice number, along with popular features like call forwarding, voice-mail transcriptions and cheap international calls. However, it’s still missing a bunch of the older service’s functionality. By signing up you’ll lose the ability to make calls and send text messages over Google Voice, the ability to view your history in Voice, and more. Overall, it sounds like Project Fi is a pretty solid substitution, though die-hard Google Voice fans may want to think twice before signing up.

Google also asks for a few other details, including your ZIP code and address. You’ll need a Nexus 6 to use Project Fi, and you can buy one while registering for the service with just a few extra clicks. If you already own the stock Android phablet, you should be able to use that device without any issues.

It looks like Project Fi invites are still going out, so hopefully we’ll know even more about the new service soon.