Phone numbers, although made up of digits, are best stored as strings in most programming and database contexts. This is because phone numbers may contain leading zeros, separators (such as dashes or spaces), and international codes that are not used in calculations as numeric values would be. Storing phone numbers as strings preserves the exact formatting and data integrity.
Reference: Basic data type handling is a fundamental topic in IT education, as discussed in CompTIA IT Fundamentals and other programming foundational guides.