A good rule of thumb is : does any of the participant maintain the backend?

If not then you are dependent on at least a 3rd party. If that 3rd party is not entirely open, meaning at least

• standards for the protocol,
• open source for the backend and frontend,
• alternative clients,
• alternative backends,
• both can be actually used (not just in theory because the protocol has been published)

then basically you should consider that this 3rd party owns your group, there is no expectation of privacy in it, it can be closed in an instant, messages can be modified without you knowing it, etc.

TL;DR: bad.

The protocol is cool, the implementation becoming proprietary and enshittified is a bummer.

Now its not just the carriers now get your texts unencrypted, apple and google do too.

Use matrix, XMPP, or simpleX if you want something private.

The carrier has to support it which is a red flag for me since they have to archive metadata and the contents.

This’ll be a hot take but anything based on Signal’s protocol (including WhatsApp) is better than RCS in all ways.

My VPN doesn’t work with RCS, which is, at best, annoying. It automatically connects when I’m on untrusted WiFi. Hopefully anyone messaging me has the “fall back to SMS” option enabled, but I’ve learned that several don’t. I learned that because I didn’t get texts from them until after I left work, (and disconnected from the work WiFi).

Even worse, group texts don’t have any option to automatically fall back. So I don’t receive any group texts at all while I’m at work, but the senders have no way of knowing that. In fact, there have been several instances in recent memory of friends/family being left out of the loop on plans, because they weren’t receiving RCS for some unknown reason, which meant they missed an entire group text conversation.

My father’s phone is particularly bad about it. It’s an iPhone, and he’ll just randomly stop receiving RCS until he toggles his cell service off and back on again via airplane mode. But who the hell would think to toggle airplane mode, when there is no indication that they aren’t receiving something? It’s a catch-22, where he doesn’t get any notification that something is wrong, because he doesn’t know he’s supposed to be getting notifications at all. There’s no way for him to prove a negative, so the only way for him to reliably get RCS is to toggle airplane mode every few minutes. Which isn’t really a feasible use-case scenario.

I can’t use it between Android and iOS because I don’t have Google Play Services and RCS requires Google Play Services and Google Messenger on Android to work. No third party app can use it.

RCS is even less secure than SMS though — it’s unencrypted and by design, Google, Apple and the carriers all have to be able to inspect the content. And the way it’s designed makes it really difficult to have an open E2E encryption standard. So as a result, Google<->Google is encrypted, Apple<->Apple is encrypted, but combine even one device not of the same type in a group chat and it has to be unencrypted.

Last I checked, there is still no way for developers to use RCS on Android, so it’s a non-starter for me. I do not and will not limit myself to first-party apps.

Please correct me if I’m wrong. If there’s an open-source RCS-compatible messaging app out there, I’d love to try it.

Doesn’t work properly on Graphene OS most of the time