Telcos know that authentication is about the only remaining use case for SMS and are not going to turn down the revenue stream.
And it can’t die fast enough, as it’s essentially the same as broadcasting your sensitive information over unencrypted radio.
Apart from security, phone number based user identification is such a half-assed approach and I still don’t get why Signal wants to die on that hill. It’s inconvenient, yet trivial, for anyone to register a second, third or tenth phone number. With a bit more knowledge and inconvenience, even anonymously. It adds so little.
Signal and DeltaChat, as well as Simplex and some others e2e communication solutions, are adequate from a technical point of view.
The main issue is always adoption. You can have the most convenient way to safely communicate with people, it’ll be useless if nobody you’re talking to wants to use it.
So, since Signal is very easy to set up and use as well as the most adopted, it’s currently the best pick for regular conversations.