About RCS


Tom dives in to the world of text messaging, explaining what RCS is and how it’s probably not what you’re expecting.

Featuring Tom Merritt.



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Episode transcript:

My text messaging includes videos and read receipts but a friend tells me I have to have RCS to do that stuff.
Do I have RCS?
And if so, why does my friend not get my videos by text?
Don’t be.
Let’s help you Know A Little More about RCS.

RCS stands for Rich Communication Services. It’s a communication protocol supported by mobile carriers for sending multimedia messages between users.
It goes under a few other names depending on the carrier, the implementation and which part of the world you’re in. You don’t need to know all the names, but if one of these sounds familiar to you– Advanced Messaging, joyn, SMSoIP, Message+ or SMS+– those are all using RCS under another name.
RCS is the successor to SMS, simple messaging service. But before we go into explaining all of that, let’s address something that may confuse some folks about messaging apps.
Messaging apps come in wide varieties but I like to think of them in two main groups, 3rd-party apps and carrier-supported apps.
Most third-party apps are easy to identify. WhatsApp, WeChat, Signal, Telegram etc. They may be linked to your phone number but your mobile carrier has nothing to do with them. Their messages are carried over the internet and therefore will not work if your data service isn’t available. Also, third party apps can implement whatever features they want because they run their whole messaging network.
The other group– carrier-supported apps– I often think of as SMS apps, though I suppose I’ll need to update that to RCS apps. These apps work with your mobile carrier’s text messaging service. Historically, SMS is not carried over the internet so there are times when you can get a text message out even if you don’t have data service, because it’s going over the part of the network used for voice calls, not the open internet.
There’s some confusion out there because phone operating system makers have mushed the carrier service into their own apps. So you get a combination of features *like* a third party app, right along side carrier-supported SMS.
Apple’s Messages app is a prime example of this. It handles the SMS service but also runs its own third-party iMessage service in the same app. iMessage needs a data connection. Hence the blue color for messages between people using iMessage and green messages for SMS. If you think of green as Android users, that’s only because there is no Apple Messages app for Android, so you only ever send SMS between iOS and Android devices.
And of course Android has had literally dozens of apps you can use as your SMS app along with an internet-based messaging service from whomever made the app, usually Google but sometimes the phone maker like Samsung or the carrier like Verizon.
Google has pushed to simplify that by supporting RCS early and pushing carriers to support the Android Messages app as the default SMS/RCS app. And they’ve had pretty good success with that.
So to sum up, when talking about RCS, we’re talking about your mobile-carrier-supported messages in the default text messaging app on your phone. Those default apps are usually Apple Messages or Android Messages or maybe Samsung Messages. Most often.
So what is RCS anyway?
The Rich Communication Suite initiative was started in 2007 and in February 2008, the GSM Association– the mobile carrier industry group– established a steering committee to pursue RCS as an industry standard. The S in RCS was later changed from Suite to Services.
Samsung launched RCS support for some of its phones in 2012.
In September 2015, Google acquired Jibe Mobile and announced it would use that acquisition to bring support for RCS to Android. And it has.
In November 2016, the GSMA published a single spec for RCS called the Universal Profile. Carriers and operating systems that follow the profile guarantee interconnection. This lets your messages go to anyone without them having to have the same exact app. That’s how SMS works too.
In 2018 Google started working with carriers on RCS implementations, and in June 2019, Google started deploying RCS in Messages.
And in some date to be added in a future update to this episode, I’m guessing Apple will announce support? But it hasn’t yet. Maybe it won’t. Who knows?
So what does RCS get you?
RCS uses your broadband connection in most cases. The times when you have voice service and not data are getting rare, so RCS is just running on the data service.
It also supports features SMS does not, like group chats, video, audio, high-resolution images, read receipts and typing indicators.
RCS also lets messages go over WiFi, not just the data connection, lets you rename chat groups and add and remove participants from a group chat. And it supports location sharing, file transfers, and voice and video calls over the internet.
Some of you are thinking or possibly even saying aloud, but I have all that already on SMS. Actually no. You don’t. You have that in your messaging app that also handles SMS maybe. But every time you send a message between Android and iOS you experience the difference. Have you had a group chat split into individual messages to each recipient? You fell back to SMS. Have you received an image that was very tiny and low-res? You fell back to SMS. Have you ever said “Video” what video? I didn’t get a video?” You have fallen back to SMS. Had a text get cut off after 160 characters? You fell back to SMS. (Side note: Twitter’s original 140-character limit was because it was originally designed as an SMS service and needed messages to fit into the SMS along with 20 characters for routing information.)
None of that fall-back behavior will happen in RCS as long as you’re messaging between apps that support RCS. Like Android messages to Samsung Messages. Or Samsung messages to Verizon Messages.
Maybe you’re thinking you might jump from Telegram to using RCS now?
Before you start the campaign to convince all your friends and family to move, let’s tell you what you don’t get.
Your friends and family on iOS. Until Apple supports RCS, if you’re messaging someone using Apple Messages, you will fall back to all those SMS behaviors I just mentioned. Same goes for anyone using any app that supports SMS but doesn’t support RCS.
You also may not get end-to-end encryption. RCS allows for end-to-end encryption but not all the apps have implemented it. Google supports it on one to one conversation and is launching it on Group chats as well. But if you have someone in the chat not using Android Messages you might not get it.
You won’t get Cross-device support. RCS has no standard way to support messaging on laptops, desktops, tablets, and watches. That one may sound worse than it is though, since SMS doesn’t support it either and lots of services including Apple’s Messages have found workarounds for it.
And RCS users also won’t get whatever the newest feature from WhatsApp, Signal or WeChat is. Those platforms and platforms like it own their own system so can add features fast even if they aren’t first to do it. RCS requires the industry group to vet it and deploy it to the whole ecosystem. With Google on board that isn’t as slow as you might think but it’s generally not the first or even second with new features. Not yet.
That’s what you don’t get.
Now before we wrap up let’s acknowledge what businesses get out of RCS. Because they get a little more.
In industry terminology, your message to your friends and family is known as P2P, which in this case stands for person to person. Even a group chat of actual people is P2P. But even on SMS there can be applications sending messages on behalf of businesses. Like your shipping notifications and solicitations for political donations. Those are known as Application to Person or A2P.
The RCS version of that is called RCS Business Messaging or RBM. It was created to address the fact that 3rd-party messaging apps were trying to win businesses over to their platforms with lots of cool features SMS didn’t have. Businesses have largely stayed on SMS, and thus paying carriers in most cases, because they know all their customers have a phone but all their customers don’t use the same 3rd-party app. So RBM is meant to keep businesses from being tempted to switch over to third-party entirely.
RBM gets all the features of RCS but also adds quick-reply suggestions, branding and richer cards and carousels. RBM requires a Messaging-as-a-Platform server which controls verified sender details. That can help cut down on SMS spam or make it a lot easier to identify it.
Right now any shady operator can just use a bunch of SIM cards to avoid paying A2P rates. With RBM it will be obvious that they’re doing that because their messages will not be RBM and not support the RBM features, particularly branding. I mean, never underestimate the ingenuity of shady operators to find workarounds, but theoretically they should be a little easier to block and spot.
If you’re already a dedicated third-party app user and never touch the SMS app on your phone RCS will mean almost nothing to you. BUT if you frequently use your default Messages app for that old fogey 50-year-old podcaster in your life who just never seems to respond to your Facebook messages pings, well, RCS will help you send a sticker or video mocking him for that.
In other words, I hope you know a little more about RCS.