Wraps Stytch's send via WhatsApp API endpoint. Call this method to send an WhatsApp passcode to existing users.
This method is also used when you need to add a phone number to an existing Stytch User. If there is a currently valid Stytch session, and the user inputs a phone number that does not match one on their Stytch User object, upon successful authentication the new phone number will be added to the existing user. Note, this does expose a potential account enumeration vector, see our article on preventing account enumeration for more details.
Cost to send SMS OTP
Before configuring SMS or WhatsApp OTPs, please review how Stytch bills the costs of international OTPs and understand how to protect your app against toll fraud.