If you want to ensure that the mobile phone number provided by the customer is correct, you can activate SMS-TAN. Only after entering the TAN can the user register or book appointments. Customers cannot enter an incorrect mobile phone number, either intentionally or unintentionally.
Example of registration with SMS-TAN:
Enforce an SMS TAN for every appointment booking
Customers can only book appointments definitively after entering the TAN sent to their mobile phone.

