Google Messages Uses The RCS Protocol: What And How It Works

The Google Messages app embraces the RCS protocol, allowing you to send “rich” messages containing multimedia files, freeing yourself from traditional SMS and MMS. End-to-end encryption is still missing.

After having recorded several flops on the side of instant messaging apps, Google recently confirmed that it wants to focus only on the Messages application, which until yesterday could only be used to manage SMS and the by now superseded MMS, and now heralds many new features.

The main innovation introduced in Google Messages for Android is the support for the RCS ( Rich Communication Services ) protocol. RCS is not an invention of Google: it is a protocol already approved in 2008 by the GSM Association (GSMA) but remained essentially unused until more recently. The RCS protocol is an evolution of traditional SMS because it combines various services while managing authentication, authorization, registration, pricing and routing. 

With RCS, users can receive sending and reading receipts, send photos and videos (even in high resolution), know if the interlocutor is answering, and involve several participants in the conversation. The RCS standard was born under the wing of the GSMA to work on mobile phone networks assuming cooperation on the part of the telecommunications operators.

In the second half of 2019, several mobile operators agreed to cooperate to accelerate the adoption of RCS. In Italy, however, only Vodafone supports it (source: GSMA data updated to 4 May 2020 ). At least in the current state and officially (it is not certain that other operators have not adapted in the meantime, even for a limited number of users).

Why Google Decided To Use The RCS Protocol: What It Is And How It Works

What did Google do? The Mountain View company had the idea of ​​embracing the RCS protocol to implement it directly in its Messages app. In this way, this application embraces a GSMA standard, effectively ignoring individual mobile phone operators’ implementation of the same protocol. Suppose RCS is not directly supported on the mobile network of the telecommunications operator chosen by the user. 

In that case, the Google Messages app will still use the data or WiFi connection to sort communications. Google’s Jibe Mobile platform acts as an “intermediary” between the various users (regardless of whether they use the Google Messages app or, in any case, an RCS-compatible mobile network and client).  Jibe provides in-cloud support to sort messages via RCS when using a mobile network that does not yet support the protocol. 

As seen in the presentation video we have republished, Google explains that it could take years for individual telephony providers to adopt a protocol like RCS. The company founded by Larry Page and Sergey Brin instead tries to force things by using the suitable link to the implementation of RCS on the cloud, thus making it possible to send “rich” messages (therefore containing texts of any size but also images and multimedia files) relying on the data network and WiFi.

To access the RCS settings, start the Google Messages app, go to the settings and then touch the Chat features item. It will read ” Connected ” when your device can send and receive RCS messages through the Google Messages app. The ” Activate chat features ” option allows you to use the data network and WiFi connection, when available, to send and receive “rich” messages using the RCS protocol.

You can also choose whether or not to send read receipts and show a typing indicator (to let various contacts know when you are replying to their messages). If an RCS message is not delivered to the recipient, Google Messages will try to send it again via SMS/MMS by default. Still, you can refrain from a new attempt using traditional SMS and MMS or ask before sending again by SMS /MMS. Furthermore, by default, Google Messages downloads files transmitted via RCS weighing up to 105 MB: it is possible to lower the threshold (to consume less mobile data) or completely disable the automatic download of files.

When composing a new message with the Google app or replying to someone else’s communication, it is important to check what the icon in the lower right corner looks like. If it shows SMS or MMS, the message will be sent using the traditional methods; if the SMS and MMS indications are not displayed, however, it means that the sending of the message will take place via the RCS protocol on the data network or via WiFi at no additional cost (it is important to make sure you have updated the Google Messages app to the most recent version; release 5.7.097 or later).

The Google Messages app pings the selected contact’s terminal to ascertain whether or not the RCS protocol is supported. There is no centralized database like, for example, Apple iMessage.

At this address, you can find more information on the functioning of the Google Messages app.

For example, Google reminds you that if you change your smartphone and move the SIM to another device, you must remember to deactivate chats via RCS in the Messages app.

Otherwise, the message-sending and receiving functions could remain active on the old one—terminal for up to 8 days. From a security point of view, all communications via RCS are client-server encrypted, and since June 2021, Google Messages has used end-to-end encryption.

If the recipient is not online, Google will keep the data on its servers until it is possible to deliver the messages. However, the company has specified that the communications will be kept on the cloud only for the time strictly necessary. Applications such as WhatsApp, Telegram (limited to the “secret chat” feature), Signal and Apple iMessage use end-to-end encryption instead.

WhatsApp has repeatedly been the target of harsh criticism from Pavel Durov, creator of Telegram: WhatsApp is unsafe: Pavel Durov accuses the Facebook app again. WhatsApp is criticized for its not very open attitude (with the code remaining proprietary and even obfuscated to make it difficult for third parties to analyze it), which would have favored the use of vulnerabilities and zero-days that remained unresolved for a long time.  The new functions of Google Messages can also be used from the web to send and receive communications from the browser (also via PC): Send messages and SMS via mobile phone.

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