You can get customer information easier from the built-in customer search tool.
Just go to the back office > Dashboard > Orders > New and click on the Select user icon next to the Name input field you will see a popup with all your customers.
In the search field in the top left corner type in the phone number and click on the Search icon.
Click on the name of the customer and their data will be auto-filled in the Order details.
Here you can search by name, email address or phone number.
You can also create a new user by clicking on the New button in the top right corner of the popup.