Some crypto exchanges requested a phone number and access to the Telegram at the same time.
Some didn't ask for a phone. But they asked for confirmation by SMS when trying to withdraw some of the money.
Is a push-button phone number enough for them? I set up important SMS messages on a push-button phone.
Friends of friends told me that when Sberbank was actively promoting the mobile version of the bank. The security staff didn't use it because they knew a lot about it.
