[bmarquez]

What you're asking for is exactly how Telegram works, you can add someone with a phone number or by username, but if you add someone via username they don't see your phone number. Of course, Telegram chats are not encrypted by default, and there is some controversy over the encryption protocol.

https://telegram.org/faq#q-if-someone-finds-me-by-username-m...

[Semaphor]

Last time I checked, the only option to login was using a phone number. And at least the web client only has the phone number as login. I do not want to give them my phone number. Full stop. They can tie my account to my email, to my domain, to a chosen username, whatever. But if your service requires a phone number to use it, it’s not something I will use.

[bmarquez]

It's still true. Telegram still uses your phone number to login, even if you never give your phone number to anybody. At least usernames are an option unlike Signal and WhatsApp.

I dislike it too, but understand the reasoning behind spam prevention and account authentication.