I have a simple customer form with the usual customer info

when i enter the phone number, I would like one of two things to happen

If customer is already on file, display all data and allow for modification

if not on file, allow for new data to be entered for the customer

seems simple enough but i am not sure if i need a subform or can i do this in one main form?

Thank you

ps: submitted this an hour ago but  has not shown up so reposting