Transmission Path Originating Address. The TPOA is the SMS header field that contains the message sender's number. The TPOA field is limited by GSM standards to: - Maximum 16 digits if the origin is numeric (for example, a phone number), or - Maximum 11 alphabet characters and digits if the origin is alphanumeric for example, a company name).
Two Factor Authentication's main aim is to be used for verification codes, 2FA and One-time Pin codes content. It can be used to secure login and sign up from unwanted visitors by verifying user possession of number or adding second-factor authentication.