Quote from: NotATether on Today at 06:28:31 AM

If from the telecommunication companies, you're pretty safe. But from governments handing over subpoenas to the telecoms for data? Less so. Don't make your service another Encrochat, have a TOS that prohibits and bans illegal use of the service (this can be accomplished by keeping temporary logs of the phone calls) so that you stay on the good side of the law.

I don't know if you knew this, but most of the things like Encrochat or Sky phones are actually created by government agencies for spying on people.

Quote from: examplens on Today at 07:43:29 PM

It's enough to receive only one SMS to activate Telegram acc, and voila.

Everything in telegram is unencrypted and stored on their servers, including calls, public chats and private messages, except maybe secret messages that have some obscure encryption claims.
This is all connected with your IP address and mobile phone number you used for registration, so there is nothing private or secure about telegram.