It is basically asking what is their relationship, and that being they have a family relationship a child with the father. The evidence is that on the top of the screen of the phone, it says "Dad" meaning that he/she is talking to their father.
1. Father and son. At the top it says DAD and talks to boy as if it’s his son. 2. The Dad missed the call. He said “ I see you tried to call”. Which leads you to understand that his missed the call. 3. That the son is having a rough time acclimating to the new school. The son said he is feeling lonely and has no friends. So it’s hard for him.