RCS is a federated protocol. Any app could use it if the network providers supplied a service for it. Google is providing a Google server fallback for if they don't.

There may not be a UK RCS market, but given it was just turned on a couple months ago and for a few countries, perhaps it's too soon to call it decided?

My point was specifically in response to Google's claim that RCS is a "gold" market for RCS where they have already completed the rollout. They haven't. They have the support of one carrier with roughly 20% market share, and about 3 - 5% of Android devices.

There isn't really any reason to surmise that is going to improve, and Google's boasting here is very silly. RCS is a dead end product in every non-US territory, and Google have no market levers to pull that can improve it's performance. They should give up on it and focus their efforts on the US bluntly.

> They have the support of one carrier with roughly 20% market share, and about 3 - 5% of Android devices.

According to Google (in the articles I read and shared here), whether the network provider supports it is irrelevant because they are supplying their own server in those cases, so it should just work. If you're in that region I'm interested to hear what you experience is if you have access to an Android phone and test.

Either the provider has to support it or the SMS app on the device has to (TBH the provider support also requires some level of integration with the SMS app but that level is more common).

Google has rolled out a provider independent implementation to it's own SMS app, but that SMS app has no marketshare.

My experience is that, without going and hunting out an app to install, my Samsung handset has no support. I have a number of test devices, some of which do have support and a few even have support by default, but those have no marketshare.