[Moto7451]

My sister had an issue with RCS not working on her Samsung. It turned out she had a SIM card too old for AT&T to support RCS on it and some Samsung related software issues related to their SMS apps and Google’s SMS apps conflicting. A fresh SIM and a couple software tweaks netted her RCS.

I’d assume this isn’t the issue here but RCS seems to be a bit fickle.

[paulddraper]

I’m curious about what part of RCS requires specialized hardware support.

[joecool1029]

There isn't specialized hardware support. As I remember Samsung had their own RCS implementation with some carriers (T-Mobile, possibly AT&T but I'm not sure there). They sunset this and moved to Google Messages. Those android devices would report which servers they used. This of course is hidden from the Apple user.

I was going to make the MMS section of this post about the 'ISIS Wallet' boondoggle that is the closest business parallel I can think of to RCS and actually did require specialized hardware support. Same 3 carriers I've been trying RCS with on the iPhone tried to make a mobile payment wallet: https://en.wikipedia.org/wiki/Softcard They rebranded it to Softcard since the 'We support ISIS' branding aged like milk. Google Wallet competed and took over the assets, sort of like what happened with RCS.

For the specialized hardware... the SIM card needed to have an embedded secure element that handled the keys for the payment system and the phone needed to support connecting to that secure element on the SIM card. I think these started to hit the market in 2010 or so, and you would have had to have a SIM card new enough to support it, here's a pic of the T-Mobile one, I had one: https://www.tmonews.com/wp-content/uploads/2013/08/Screen-Sh...