Nowadays, online life has greatly changed the way we make friends. If I were you, I would only have the phone numbers of people I often contact in my mobile phone. Generally speaking, the stored number will not be deleted on purpose, but if I change my mobile phone number or format my mobile phone, I won't ask someone else's mobile phone number again. What does it matter if you don't look up and see a mobile phone number? Maybe he has your phone number in mind, or you are too good to communicate by phone. A hedge between keeps friendship green.