The European Payment Services Directive (PSD2) requires Strong Customer Authentication (SCA) for electronic payments over €30, which applies to businesses and customers in the European Economic Area, online/debit or credit card-not-present transactions, and other remote actions that may imply a risk of payment fraud. Twilio offers three ways to implement SCA: Verify SMS One-Time Passcodes, push authentication using the Authy App or embedded into an application, and transactional TOTP, which can be used with the Authy API and Authy App for offline authenticator support. To comply with SCA requirements, two-factor authentication is needed, using a combination of factors such as inherence, possession, and knowledge elements, including dynamic linking information about the transaction, such as payee, payment amount, and option to include additional context fields like this.