The Clear Down trophy is for answering all optional phone calls in the game. The game doesn’t give the number of phone calls, but I did get the trophy for it and this is a list of the 13 phone calls I made/answered.
- Accommodations – After Engineering, turn right when you first enter Accommodations on the Utility level.
- Life Boat – By the one you launch. It’s on the stairs going back up to Accommodations. Head up the stairs and interact with the door and it’ll start to ring. Answer it and Rennick will tell you how to open the gate.
- Above Life Boat – As you’re climbing your way back up from the Life Boat, this is after the fire. Before the ladder heading up to the Utility Door.
- After the helicopter crash – When you go back down, head into Rennick’s office instead of going the other way.
- After helicopter crash – As you leave Rennick’s office it’ll ring again.
- Administration – As you enter Administration, the phone is in the room on the right.
- Starboard Side – After interacting with the helicopter, and going down the scaffolding, this is inside.
- Engineering visit #2 – After you turn the generator on, head back to the Protective Relay and pull the lever. After that, then the phone will ring.
- Accommodations visit #2 – Locker room phone. Not sure this one counts since it’s required, but call Roy.
- Accommodations visit #2 – Locker room phone. After talking to Roy, go to leave and it’ll ring again.
- Accommodations visit #3 – When you enter into the hallway at start, pry the lock off the door to the left. When you go through the door, the phone on the wall next to the map will ring. You have to go through the door to trigger the ring.
- Entering the Roof – After the cutscene with Roy. Same room.
- Entering Marine Control – After the flooded hallway, this is in the office you climb up into.
See other trophy information in the google workbook.