Following the formal reveal that Google is rolling out its flavor of RCS in the US, we had a few lingering questions, like what happens to folks that previously used the "hack," has the security used by Google's RCS changed at all to accommodate the US market, and is Google going to open its solution up for other messaging apps? (All among a longer list of even more technical questions.)

We reached out to Google and put together a little explainer for the subject that should make everything a little easier to understand.

What is RCS/chat?

RCS is a terribly complicated subject in general. To start, there's a set of messaging standards called RCS, or "Rich Communication Services," which is basically a next-gen replacement for SMS/MMS messaging. There are many implementations and versions of the RCS standard that add individual features, but in general, they allow you to send messages and media (photos, videos) between RCS-compatible phones/phone numbers over data connections, including Wi-Fi, with instant messaging-like benefits including typing indicators, read receipt notifications, and group conversation support.

The GSMA's (GSM Association) preferred implementation of RCS is called the Universal Profile, and it's a set of RCS standards agreed upon by several different companies and organizations to ensure interoperability — standards don't mean anything if everyone doesn't use the same ones, and the Universal Profile is, objectively speaking, the standard for RCS. Sadly, some RCS implementations used by carriers haven't stuck to that Universal Profile, which means the extra messaging features are sometimes locked to specific devices or only work inside a given network. If you're using a solution like that, it means if you don't have the right device on the right network and your friends don't have the right device on the same network, you can't use these new RCS features with them.

Thankfully, Google's solution pretty much fixes that problem, though there are still some requirements.

Google brands its flavor of RCS in the Google Messages app as "chat" (in varying capitalization), and it uses a Universal Profile-compatible cloud-based network Google bought/built called "Jibe." Since it meets Universal Profile standards, Google's implementation can send messages successfully even outside the Jibe network with other Universal Profile-compatible solutions, so long as they connect with it. In short, that means Google's chat should be pretty much the best possible combination of standards, though it does require Google's Messages app to work.

What sort of security and privacy is built in?

We also took a deep dive into Google's RCS-related support documentation, which illuminates some of the details behind everyone's new favorite chat protocol. Based on the current description of RCS's security, it doesn't appear that the company has changed how things work in chat since it described those details to The Verge earlier this year.

In short, although messages are encrypted in transit, they aren't fully end-to-end encrypted. They're also deleted from Google's servers as soon as possible:

  • If your message is sent and delivered successfully via Google's RCS, it's then deleted from Google's servers.
  • If your message is sent via Google's RCS, isn't received, and you ultimately have to fall back to SMS/MMS, it's also deleted from Google's servers.
  • If your message is sent via Google's RCS, routed through another provider, and successfully delivered, it's deleted from Google's servers — though other services in the chain may have their own data policies.

However, files like images and videos sent in RCS messages are temporarily stored on Google servers with non-visible, hashed, "random, unguessable URLs." Be careful who you send files like images to, as well: Metadata isn't removed from photos, so if location data was attached when it was captured, that is sent to the recipient, too.

To route your messages and enumerate which of your contacts can and can't receive RCS messages, Google stores some information like your phone number, SIM, and other device identifiers while you're connected to its RCS/chat protocol, though that information is eventually deleted after about a month if you opt out or become inactive. Should any of this bother you, just don't opt in when you get the prompt on your phone.

What do I need to use Google's RCS?

"We are working on bringing chat features broadly to more regions, carriers and other messaging apps (e.g. Samsung Messages)."

Google's RCS/chat requires a recent-ish Android phone (if for no other reason then due to the app's minimum requirements), and it's only available to folks in a handful of markets. Including the announcement of the US rollout by the end of the year, it's also available in France, Mexico, and the UK. The Google Messages app is also a hard requirement right now (outside some carrier collaborations like Rogers’ and Sprint’s use of Jibe) but it sounds like the company would like to open things up to other apps in the future, stating that "we are working on bringing chat features broadly to more regions, carriers and other messaging apps (e.g. Samsung Messages)."

Developer: Google LLC
Price: Free

You may also be prompted to exclude Messages from battery optimization on some devices to ensure that RCS works it should, since it requires a constant connection to function.

As always, RCS will fall back to SMS/MMS if RCS isn't available for a given contact or if you lack data. You can even set the logic for when and how that fallback occurs (in the Messages app -> three-dot menu -> Settings -> Chat features -> Resend messages if undelivered). If you weren't otherwise aware, Apple has yet to support RCS messaging on its devices, further increasing the divide between iMessage bubbles — though Apple may have to relent and add support if it wants to use the official GSMA 5G logo.

Google also reiterates that the Messages-provided RCS/chat features are free, though you are responsible for the cost of any associated data.

How do I enable Google's RCS?

If you're in a market that already has it (France, Mexico, or the UK), you should see a message prompting you to enable "chat" when you open the Messages app for the first time. If you're in the US, you're stuck waiting until the rollout hits your device, or you can switch to the current "hack" which puts you on one of Google's sandbox servers — unless you're terribly impatient, the easiest thing to do is just wait.

You can't manually opt in on the US rollout.

If you were hoping to jump to the head of Google's RCS line as the feature hits the United States, that probably won't happen. You can't manually opt in on the US rollout. However, if you miss or skip the notification to enable RCS in Messages once you get it, you can manually go back and enable it later via the three-dot menu -> Settings -> Chat features. That's the same place you can check your current connection status, which is an indicator that you're set up and ready to use RCS with compatible contacts.

We've seen a smattering of reports which claim that Google's solution is rolling out (one of our own devices that never saw the "hack" is now connected to Google's carrier-specific Jibe servers), but it's slow going. Google's initial timeline had "broad availability" set for the end of the year, so there's still some time left.

What happens if I used that RCS 'hack?'

According to Googler Sanaz Ahari Lemelson, those that used the "hack" to get RCS on their phone in the US a bit early will be transitioned after the official rollout is complete. There's also no way to opt in on the rollout, so if you're impatient to get Google's officially-sanctioned version, you'll just have to wait until it lands or resort to that hack.

What happens if I enable chat/RCS and switch away from Google Messages?

Google may keep your phone number registered as chat-compatible for "about" eight days after you last connect.

Google's RCS solution only works via the company's own messaging app. That's at least partly because RCS support doesn't work at an app-independent system level like SMS and MMS do (yet). So if you switch devices or apps after your phone number has been registered, you could run into issues with missed messages, much like the issues you'd experience if you switched away from an Apple device without first "deregistering" it from iMessage. That's because once your phone number is registered with Google's servers, anyone else using a Universal Profile-compatible RCS messaging service will attempt to send you messages via RCS rather than SMS.

Google may keep your phone number registered as chat-compatible for "about" eight days after you last connect, which may result in significant message delays during that period. There are rules in place that eventually result in messages falling back to SMS/MMS, though. In our anecdotal testing, messages sent to you via RCS that can't be delivered via RCS typically fall back to SMS within minutes, though other reports have claimed it can take longer. We have confirmed with Google that the 8-day maximum is something of a worst-case scenario, and we're told that "de-registration can happen much faster depending on device and SIM configuration and handling."

Unlike iMessage, Google doesn't appear to have an easy website for deregistering your phone number from its RCS servers, either. You can, however, opt out in the Google Messages app itself before swapping between devices or apps (though that doesn't help you if you broke your Android phone and switched to iOS). To disable RCS so you don't run into this issue, open the Messages app, and go to the three-dot menu -> Settings -> Chat features -> and toggle "Enable Chat features." The "Status" section at the top of the Chat features pane should then disappear. After you disable chat, your phone number should be deregistered from Google's servers.

Google plans to add a deregistration method outside the Messages app eventually.

We reached out to Google for more information about deregistering from its RCS service, and the company told us that it's "actively working on expanding [deregistration] to make sure it's convenient for users, including making it faster and easier to disable if you don't have access to the Messages app." While they wouldn't tell us anything explicit, it's clear Google plans to add a deregistration method outside the Messages app eventually.