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

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.