How to check the contact information for previous owner for the cell phone?

One of my friends' father hasn't contact any of the family members for 8 months. They are very worry about him. My friend called the number they had the last contact with, but the new phone owner doesn't really know his father. Does the cell phone company stores the contact information for the previous owner? If not, how do you go about to check if that person is alive? Go to city hall to check for death record?|||hire a detective|||Research it.