The curse of SMSAugust 23, 2021
SMS was, and remains, the one unifying messaging service available on all GSM phones by default. SMS has been superseded by RCS, which provides the instant-messaging-via-Internet features we’ve come to expect from 3rd-party apps.
But RCS adoption among telcos has been sporadic and inconsistent. Because of this, Google provides its own RCS server to all Android users globally. Unfortunately, due to privacy concerns, the feature is not enabled by default. (You have to go to your Messaging app settings to turn it on)
20 years ago, the problem between telco dominance and 3rd-party commercial apps was solved with open-source federated platforms like XMPP (Jabber). Such open systems allowed anybody to develop apps and services that all worked with each other. Every Android phone in the world came with an XMPP client by default (Gtalk), and you could install any other if you wanted. This system has long been forgotten.
SMS remains a major revenue channel for telcos to this day.