telegram_otp — a code from Telegram

We generate a code and deliver it to Telegram through the official bot; the user enters it on your side and you submit it for checking.

What to watch for

• The user needs Telegram on that number. With no account there is nowhere to deliver the code — have a fallback method ready.
• On a wrong code the 400 invalid_code response carries attempts_remaining; once attempts run out the session moves to failed.