Deter Obnoxious, Nefarious, and Outrageous Telephone Calls Act of 2021 or the DO NOT Call Act of 2021 This bill increases and establishes criminal penalties, which include imprisonment for up to one year, for an intentional violation of the prohibition on automated telephone marketing and messaging. In addition, a person may be imprisoned for up to three years for an aggravated violation of such prohibition if the person (1) previously has been convicted of such an offense, (2) initiates a certain high volume of such calls during specified periods of time, (3) commits the offense in the furtherance of a felony, or (4) causes losses of at least $5,000 during any one year period to one or more persons. The bill also increases from $10,000 to $20,000 the fine for intentionally transmitting misleading or inaccurate caller identification information.