Pinpoint RSVP System

Team -- I am looking to create an SMS based RSVP system that should --

a) greet the user based on 'OriginationNumber' .. for instance, if the text message is coming from +18001234567, the response back should be a greeting with the user's name based on a details in the file imported as part of a segment

b) present a small menu the user can interact with and confirm their attendance

c) save all responses to a csv or text file

Question I have is on a). Once Pinpoint receives a SMS from an 'OriginationNumber', how do I automatically greet the user tied to the 'OriginationNumber'? I suspect I have to import a file with all phone numbers and run a lambda function to compare the 'OriginationNumber' with the file and return the associated name?

Any help is greatly appreciated for this new Pinpoint user.