Other contributors have said "What is primary phone number?" is the same question as "What is the meaning of a primary phone number?" If you believe that these are not asking the same thing and should be answered differently, click here
i would assume it means your home telephone number that you might find in the telephone book and not a cell phone number you carry with you. and not the number you may have a fax machine on or if you have a home-based business phone number.
well it's something that helps you connect with other people you dial it into your phone and u can speak with your mates otherwise in your case imaginary friends since you dont know what a phone...