[viktorcode]

> You still need one to register

Case in point: recently, some Russian mobile service providers started blocking registration SMS for popular messengers, Signal included.

In earlier years there were also cases of mobile number spoofing in the country, where the control over the number was given to law enforcement who then use it as second factor authentication to break into different accounts.

That's how easy it is. The word "secure" and "mobile phone number" are the opposites of each other.