Step 4
Next, BotFather asks you to give the bot an alias (username). The username must end with "bot". Only Latin letters, digits and underscores are allowed to be used as an alias. The minimum length of an alias is 5 characters. The alias cannot be changed in the future.
Make up an alias for the bot and send it in a message. We have given the bot the nickname "ChatbulletTelegram_Bot":