If you find all the the burner phones in Watch Dogs you’ll be able to find out the secret behind Maurice’s failed attack on Aiden.
As soon as you clear the ctOS System and ctOS Towers in the area, burner phone locations will appear on the map. The audio files you get from each phone play out in a set order so it doesn’t matter in what order you pick up these phones. Once you have all eight you’ll unlock the Sanity Check trophy or achievement.
Burner Phone 1
To start you off this phone is part of the story. You get it on the opening mission. Easy.
Burner Phone 2
This is in the Pawnee district, to the north, on the roof of the motel behind the last letter. You can climb up the yellow ladder on the left when you’re facing the building and walk over the roof to find the phone.
Burner Phone 3
Another one in the Pawnee district, this is in a shed behind a restaurant serving the fattest hot fish sandwich. Through the gate to the left of the building, the shed is at the back on the left, with the phone inside a tool box.
Burner Phone 4
The last one in the Pawnee district. Go to the trailer park and at the back left hand side you’ll see a trashed blue car nearby. You’ll find it if you climb on top of the roof.
Burner Phone 5
Head to the Loop district and there’s a tent city for the homeless under a freeway. This phone is lying near a fence on someone’s bed in a home made from boxes.
Burner Phone 6
This phone is in The Wards in a courtyard between two nasty-looking apartments. It’s on the third floor of a burned out and abandoned building.
Burner Phone 7
This is one of two phones found at Brandon Docks. Inside an industrial building where you need to hack a big gate to enter. Up the stairs, turn left then right and you’ll come across the phone on a mattress in the corner, not far from a burning barrel.
Burner Phone 8
While you’re in Brandon Docks head to another industrial building. Go up the stairs on the right and when you hit the top the phone will be on a desk.
Getting all these Burner Phones unlocks the Sanity Check trophy/achievement.