I'm thinking of keeping the phone that I found
What would you do with the phone you found?
I'm going to make good use of the phone and read many interesting novels on it
If you find property that was lost by the original owner, you are obligated to return it to the owner. Keeping a lost item for your own use, without taking reasonable steps to reunite it with its true owner, is a form of stealing.
It's not like the owner is looking for it or asking around. For all I know, they could be dead.
You should still try to find the original owner. Try calling the numbers in the phone to figure out who it belongs to.