What is a valid phone number?
A valid phone number includes the country code, area code, and subscriber number. Specifically, the number matches the E.164 format. E.164 is a standard for the phone number structure used for international telecommunication. Phone numbers that follow this format typically have up to 15 digits. They are prefixed with the plus character (+) and the country code.
For example, a valid US phone number is formatted as +14085550100