Simplicity is a key selling point of Google's Project Fi wireless service (officially known as Google Fi, as of late 2018). If you're coming to the service as an existing user of Google Voice, though, things can get awfully complicated.

I've been using Project Fi for the past couple weeks as I've been getting to know Google's new Nexus 5X and Nexus 6P phones. As a long-time Google Voice user myself, I had a lot of questions about how moving into Fi would work -- and the documentation on the subject proved to be pretty limited and confusing.

You can find a broader overview of Fi itself in my real-world analysis of the service (and you can find a detailed look at Google's new Nexus phones in my in-depth 5X and 6P review). Here, we'll focus specifically on the subject of Project Fi-Google Voice integration -- and tackle all the questions you need answered.

(Quick disclaimer: This story was written in 2015, though its Google-Voice-specific info remains accurate as of 2018. The info on this page applies only to people who currently use the Google Voice service and are considering Project Fi, meanwhile. If you don't use Google Voice (or aren't sure what Google Voice is!), you'd be better off skipping this FAQ and jumping right over to my 2018 Fi FAQ instead.)

All right -- ready? Let's do this:

Is Project Fi the same thing as Google Voice? Or does Project Fi take over Google Voice? Or what?!

The easiest way to think about it is that Fi uses the same underlying technology as Google Voice. It's not the same exact thing, but it does bring over many of the features you're used to (we'll get into the specifics in a minute) -- and it does essentially take over the GV service for your account.

In other words, once you're using Project Fi, you'll use Project Fi; you won't use Google Voice. But you will end up having many of the same features and experiences.

Should I port my Google Voice number into Project Fi when I sign up?

It's really up to you, but if you like your Google Voice number and want to continue using it with your cell phone, then you probably should. That's the only way you'll be able to make and receive calls from that number using your regular cell service.

Can I port my Google Voice number into Fi even if I have GV-Sprint integration?

You can -- but there are a couple extra steps involved. Basically, you have to first disable the Sprint integration, then port your number into the regular Google Voice service before you start your Fi signup. You can find detailed instructions for both steps on this support page.

What happens to my carrier number if I port my Google Voice number into Project Fi?

Technically, nothing; if you port in your Google Voice number, Fi won't even know your carrier number exists. So you'll probably want to go ahead and cancel service with your old carrier manually once you've gotten your Fi service up and running. Otherwise, you'll be paying for service with Fi and with your previous carrier, which is presumably not what you want.

Just be warned: Once you cancel service with your old carrier, your carrier number will vanish into the digital ether. Unless...

What if I want to port my Google Voice number into Project Fi but also keep my carrier number?

The best of both worlds, right? You can actually do that -- in a roundabout way.

Remember, as we just said: Porting your Google Voice number into Fi won't actually affect anything with your carrier-connected phone number or your current carrier service. So go ahead and transfer your Google Voice number in when you're ready to start using Fi. If you want to keep your carrier number, though, don't cancel your old carrier service.

So what to do instead? I've got two options of varying complexity for you to consider:

Option #1: The Google Voice workaround

Once you're sure you're ready to kill off your old service, start up a new Google account (or use an existing secondary account, if you already have one) and head over to the Google Voice website while signed into that account. Click the option to start using Google Voice by bringing in your existing mobile number, then follow the steps to port your carrier number into Google Voice on that account.

Let me emphasize: This will cause your existing carrier service to be cancelled. Do not do this until you're ready to have that happen.

Once the number port has finished, your old carrier number will belong to that Google Voice account -- and you can use the GV website to manage how it works and where it forwards. The catch is that you can't forward a Google Voice number to another Google Voice or Fi number, so there's no real way to have both numbers work on your Fi phone.

The best you can do is to set up Google Voice so that it forwards any voicemails and text messages for that second number to your email (see the Voicemail & Text tab of the GV website) -- which is better than losing the number altogether, if that matters to you.

Option #2: The Ring.To workaround

Want more? You can do the same thing described in option #1 using a free third-party service called Ring.To instead of Google Voice. The advantage of this setup is that it'll allow you to have calls and texts to your carrier number forwarded to your Fi phone -- something that isn't possible when you're using two Google-associated numbers.

The downside (if you want to call it that) is that you're relying on a free service that isn't run by Google, which inevitably raises questions about how the company is making money and how long such an arrangement can last. For now, though, it's here and it's completely free -- and it works quite well, in my experience.

If you want to give it a whirl, head over to Ring.To's website and start the process of porting your number in. Once you've done so, you'll find an option to edit the settings for your number in the Ring.To dashboard. There, you'll find fields for configuring your number to ring one or more phones -- and yes, a Fi device will definitely work -- as well as fields for telling the service to forward incoming text messages to your Fi number or any other number you want.

The catch is that while you will receive any text messages that are forwarded to your Fi number, you won't be able to respond to them directly. (Short explanation: Texts will arrive from your own Ring.To number, with the actual sender's number included as part of the message. So to respond, you'll have to start a new message thread with the sender's number.) You'll at least get all calls and texts to your carrier number on your Fi phone, though -- and if you want, Ring.To will even let you set up an SMS auto-responder, so you could notify anyone who texts you at that number that it's no longer your primary line.

UPDATE [12/2018]: Ring.to is no more, but you can set up something similar at a minimal annual cost with other VoIP services such as Anveo and Phone Power.

What if I want to port my carrier number into Project Fi -- but also keep my Google Voice number?

Whew -- you're really making me work today, aren't you? If you want to keep your Google Voice number without bringing it into Fi, you've got a few options:

Option #1: Use a different Google account to sign up for Fi service

Easy, right? Just use any other Google account for the Fi setup, and your current Voice number won't be involved. This isn't entirely ideal, as things will be simpler to manage if Fi is associated with your primary Google account, but it's one way to get the job done.

Option #2: Transfer your Google Voice number to a different Google account

Before you sign up for Fi, move your Google Voice number to a secondary Google account by following the steps on this Google support page. That'll allow you to keep your number and leave it in Google Voice with a different account while moving forward with a new number for Fi on your primary account.

Just remember that you can't forward calls from one Google Voice number to another Google Voice or Fi number -- so if you do this, you won't be able to receive calls to your old GV number on your new Fi phone. (Fee, fo, Fi phone. Will a Fi-based rhyme make everybody groan?)

Option #3: Transfer your Google Voice number to Ring.To

The Ring.to service I described in the previous question can work in the same way here, and it will allow you to forward calls and texts to your new Fi number. Just follow the steps described in option #2 from the previous question, only transfer in your Google Voice number instead of your carrier number.

UPDATE [1/18/16]: As noted above, Ring.to is gone, though subscription-based services such as Anveo and Phone Power can still achieve this same thing (at a minimal annual cost).

What about the Hangouts Dialer app? Can I still use that to make and receive calls from secondary GV numbers once I'm using Project Fi?

Yes: If you have a second Google Voice number connected to an alternate Google account, you can use the Hangouts Dialer app to make and receive calls with that number on your Fi device. Just remember such an app works only over data, and you'd be able to make calls only through the app's interface -- so you wouldn't be able to use your second GV number with the regular Phone app or your regular cellular service.

Okay -- that's all way too complicated for me. What if I just transfer my Google Voice number into Fi? Can I get it back later if I decide I want to jump ship?

Finally, one that's easy to answer! And honestly, this is probably what most people will want to do. If you move your GV number into Fi and later decide you don't want to keep using the service, you can choose to transfer the number back out of Fi and into Google Voice. You should get an option to do so upon cancelling your Fi service; if for some reason you don't, contact Fi support, as this is definitely something that the service allows.

Do I still need the Google Voice app on my phone once I'm using Project Fi?

Nope -- no need for it whatsoever. Uninstall that sucker. Uninstall it hard.

Will I still be able to forward my calls to different numbers with Fi, like I can now with Google Voice?

Absolutely: Regardless of whether you bring in an existing number or get new digits, you'll find an option in the Fi website and mobile app to set up your number to forward wherever you want. If you transferred in your GV number, any forwarding settings you had configured before will automatically carry over. The only limitation, as we've mentioned, is that you can't forward to other Fi/GV numbers (which is also true with your current GV setup).

What about other Google Voice features? If I transfer in my GV number, will I still be able to do all the same stuff once I'm on Fi?

You'll be able to do a lot of the same stuff, but not all of it. And the apps and Web interface for controlling everything are actually a lot nicer than the embarrassingly dated Voice setup that's been stagnant for ages.

With Fi, you can place and receive calls and texts and also check voicemails via Hangouts on any device or computer where you're signed in. You also have access to call blocking (any numbers you've already blocked in Google Voice will carry over, and moving forward, you can most easily block new numbers via your phone's Contacts app).

Your call and voicemail history from Google Voice will remain available through a legacy link at the bottom of the Fi website. New histories will be accessible only in the Phone app or Hangouts.

Your text message history will still be available in Hangouts, if you were already using Hangouts for texting. If you weren't, the official word is that you'll lose your text message history upon moving to Fi -- but as of now, at least, I'm still able to see all of my old stuff via that same legacy link I mentioned a minute ago.

You still get voicemail transcription -- within your Phone app as well as within Hangouts -- and you still get the same international calling rates as before.

You can still use Google Voice's do-not-disturb and call screening features, if you want, but you'll have to go through the legacy GV site to re-enable them once you've made the move.

The GV features that you won't have with Fi, meanwhile, are spam filtering, call recording, call switching, customized incoming caller ID (i.e. choosing to have your number displayed on caller ID instead of a caller's number -- not sure why anyone would want that, anyway), on-the-fly conference calling, text-message-to-email forwarding, automatic blocking of outgoing caller ID (though you can still do that manually by dialing *67 before making a call), and the ability to make calls or send texts from the Google Voice website or the old Google Talk system (though you can still do all of that through Hangouts, so it's really not a big deal).

If I transfer my Google Voice number into Fi, can I still use the Google Voice app to route calls on other Android phones?

This question is really specific, I realize, and probably doesn't apply to most people -- but as a guy who uses a lot of different phones, it's something that affects me. And since there isn't much in the way of official info about this issue out there, I thought I'd go ahead and answer it here in case anyone else needs to know.

The short answer is yes: If you port your Google Voice number into Project Fi, you can still install the Google Voice app on an alternate Android phone and set it up so that its calls will appear to come from your Fi/GV number (and any calls placed to your Fi/GV number will ring on it as well).

If you move around between multiple phones, this should be a relief. If you don't -- well, disregard this and do a little dance for the rest of us, would ya?

If I port my Google Voice number into Fi, can I still access the Google Voice website?

Yes -- but you have to first get to it through the Fi website, using a link at the bottom; otherwise, the Voice URL will just redirect you to the Fi site by default.

That being said, you'll probably find it easier just to use the Fi site for most things. I really haven't had a need to get to the old GV website at all since I switched over. But it is still there if you for some reason need it.

What happens to money I've added onto my Google Voice account?

If you've put money on your GV account as credit -- for international calls -- it'll move over to your Fi account as soon as you make the transition. It'll just show up as a credit on your account and will be applied to your first payment.

Can I still use an OBi device if I transfer my Google Voice number into Project Fi?

Not exactly. OBi devices, if you aren't familiar, are inexpensive little boxes that let you use Google Voice to get free "home phone" service with a traditional lineline-style phone.

Officially, Project Fi is not compatible with OBi devices. That being said, I use one myself and have found some ways to make it work.

First of all, though it isn't technically supposed to, my Google Voice number continued to ring my OBi device even after I ported the number to Fi. So take that for what you will.

Following the transition, however, I was no longer able to make calls via my OBi box from my Fi/GV number. Best I can tell, there's no real way to have that happen.

The closest workaround I can offer is to set up a new number with Ring.To, the same service mentioned a couple of times above, and configure it to work with your OBi device. The base service is free, but you'll have to pay a $15/year fee in order to add 911 service to the line (which is strangely required). You also have to have an OBi box that was purchased after May 1, 2014 in order for it to work -- so if you have an older OBi, you'll have to pick up a new one (somewhat annoyingly).

Once that Ring.To line is up and running on your OBi box, you can set up your Fi/GV number to forward to it -- and you can make outgoing calls from your Ring.To number (think of it as your "office line" or "home number"). It isn't perfect, but it'll at least let you get calls to your main number reliably -- and 15 bucks a year really isn't bad for "home phone" service, if such a thing is useful for you.

UPDATE [12/2018]: Ring.to discontinued support for OBi devices a couple years ago and is now completely gone. The best alternatives I'm aware of at the moment are OBi's two other officially approved services: Anveo and Phone Power.

Neither service is free, unfortunately; Anveo starts at $40/year while Phone Power starts at $35/year. If you'd already signed up with Ring.To and paid for a year of 911 service, Anveo has the advantage of allowing you to apply any unused credit toward a new full-service plan. Phone Power is obviously a bit cheaper outside of that. Both support 911 service and both allow for unlimited incoming calls and a limited amount of outgoing minutes (333/month with Anveo's starting plan and 300/month with Phone Power's).

Annoying, I know.

Cool. Oh, wait -- one last thing: WHY IS THIS SO FRICKIN' COMPLICATED?!

Now, that's a good question. The best I can say is that Google Voice is a pretty complex service, and those of us in the power-user camp use it for some pretty involved and unusual purposes. With Fi, Google seems to be working to bring over the core pieces of Voice while shedding (or at least downplaying) some of the more advanced and niche-level features.

Let's keep things in perspective, though: For most people, none of this stuff is relevant -- and moving into Project Fi is as simple as can be. For those of us with intricate Google Voice configurations, the process is just a little more involved.

The one thing I can assure you is that once you get the transition figured out, Fi itself is completely straightforward -- and it's all smooth sailing from there on out.

Hopefully the info on this page helps you navigate the murky waters and make your way into the calm open sea.

Whoaaaa, Nelly. You're gonna end with that metaphor? Seriously?

All right, you. No more questions. And don't call me Nelly.

[Project Fi revisited: 6 months with Google's weird wireless service]