A consultant is looking to create a guided screen to be used by customer service agents answering the phone to authenticate the caller and positively identify them. The agent will ask the caller to provide their full name and the last four digits of their social security number, which is not stored in Salesforce. The agent will enter the provided information into a form, and upon clicking submit, a web service call is made to an external authentication service to authenticate the caller.
What should the consultant do to fulfill the needed requirements?