I setup an account with Twilio and was able to get a trial phone number and send a SMS message using curl in all of about 15 minutes. Their online console worked flawlessly and was very impressive.
I created a support ticket to ask specifically about RCS, even though it still seems to closed to general users.
I can probably develop my application using SMS, then upgrade to RCS whenever it is available. Not ideal though.
Here’s a RCS testing bot thanks to a user on reddit:
http://kitchen-sink-bot.appspot.com/
They’re calling it an RBM (RCS Business Messaging) bot.
Signed up for interop’s RCS community. Haven’t heard anything yet.
Requested access to their RCS beta.
A trove of information here: https://www.androidcentral.com/ccmi-faq-us-carriers-rcs-google
There’s helpful information on the “Cross-Carrier Messaging Initiative” or CCMI. This appears to be an agreement by major carriers (verizon, etc) to implement Universal Profile.
I was able to setup a self-serve demo with Quiq pretty easily. However, there doesn’t seem to be any RCS support.
Update: Their customer service was very helpful, but their focus is on customer engagement solutions.
There’s some sort of closed beta for Samsung: https://rcs.developer.samsung.com/services/about
Informative article from theverge: https://www.theverge.com/2019/6/17/18681573/google-rcs-chat-android-texting-carriers-imessage-encryption
There doesn’t seem to be an easy way to get started with RCS through Google without going through one of their many partners.
https://jibe.google.com/partners/messaging-partners/
There doesn’t seem to be a way to just sign up and send RCS messages through Twilio. Requested more information via their site.
RCS Universal Profile Spec: https://www.gsma.com/futurenetworks/resources/rcs-up-2-4-uni/
Good ol’ wikipedia: https://en.wikipedia.org/wiki/Rich_Communication_Services
IMS wikipedia: https://en.wikipedia.org/wiki/IP_Multimedia_Subsystem