Locate the hidden cell phones to find out more information about the current mission. You will know when you are near a phone when you hear it or see it flash.

White's Estate
Go through the boathouse and the first greenhouse. The one is on the wall where you shoot the helicopter.
Go towards the mansion on the left. Look on that table with the chairs.
Enter the mansion from the cellar. Look near the steps.
Go through the wine cellar and enter the black and white tiled area. Look on a table to find a phone.
Go through the mansion's kitchen and dining room. The next room has stairs. Look between the vases on the raised area at the base of the stairs.

Siena
When the mission begins, go to the metal tables and chairs to the left. A phone is on one of the tables.
Climb through the house window and enter the bedroom. The phone is next to the bedside lamp.
Cross the rooftops and drop down onto a lower roof. There will be an ammunition crate to the left. Continue into the building to find a phone directly in front of you.
Jump across a gap and enter into the house. Go through the open green doors. Go to the top of the large staircase in the next room Look on the ground before the hole to find the phone.

Opera House
Start the mission and bypass the camera. Continue to reach a step ladder with a phone, just before crossing the water.
Enter the backstage area. Climb the red steps with black and yellow marks. Look to the left to find a phone.
Continue after the sniper and walk across the beam without falling. Look to the right after crossing the beam.

Sinkhole
Make your way up the spiral slope just after the area you defended with the crashed helicopter. The phone is to the left as you are moving up that slope, before defending Camile.
Shanty Town
There is a bar immediately after you make your way across the entrance. The phone is on the counter.
Walk across the beach and enter the building. Continue ahead and look on a table to your right to find a phone.
Exit the building with the previous phone. Climb the ladder in front of you to find the phone.

Science Center Exterior
Turn around when the mission begins. Look near the ammunition crate to find the phone.
Enter the parked trailer in the alley. The phone is on a crate.
Continue after the parked trailer and unlock the door. Look to the left when you enter to find a phone.
Enter the outdoor parking garage with a white truck and two parked trailers. The phone is in one of the trailers.
Get on the rooftop and walk to the left side. The phone is next to the red pipes.

Mission Science Center Interior
The phone is to the left of the first guard.
Clear the area with two guards to reach a walkway leading to two locked doors. The phone is on the walkway between both doors.
Continue forward after entering the office area. The phone is on the desk on the left.
Enter the room with the Access Elevator switch. The phone is in the closed office next to this room on a desk.
Leave the falling elevator. The phone is on a crate to the right.
Climb out of the elevator. From this floor, go down the stairs to the floor below. The phone at the bottom of the stairs.

Miami Airport
Exit the room when the mission starts. Enter the opposite doorway. Look on the desk next to the corpse to find the phone.
Uploading to the second computer. Enter the dark office. There is a phone in a unit near the end of the office next to the third server room.
After the server room ambush, enter the dark area with the white van. The phone is to the right.
Enter the baggage area. Walk to the end of the room in the left corner on the ground floor to find the phone.
Enter the other baggage area after the door shuts on you. Climb the ladder, then use the staircase on the right to reach an office. Enter the office to find the phone.

Montenegro Train
Go into the next compartment on your right when the mission starts.
Drop down into the train car from the roof. The phone is near the ladder.
Jump across to the freight train and make your way through the cars. The phone is to the right next to the first ladder you must climb.
Re-enter the passenger train and make your way through the cars. The phones is on a crate in the second car.
After climbing to the roof of the train again and dropping down by a ladder, turn around to find the phone.

Casino Royale
Immediately after the mission begins enter the room to the right. The phone is next to the television.
Enter the apartment. The phone is inside the bedroom on the left.
Enter the second apartment from the outside after the fight. Continue along until you reach a set of double doors to the left and a single door to the right. The phone is in the room on the right.

Barge
Immediately after starting the mission you will find a hut on the right, with a television and the phone.
Rescue Vespa then go down the stairs. The phone is on the right, next to a lathe, just before you go outside.
After going back outside, move directly to the left. The phone is on a crate at the far end next to a set of stairs leading on the barge.
Walk on the gangway to get on the barge. Directly opposite that gangway at the far end of the barge is a large container that has the phone.
Continue along the right side of the ship to find a doorway, Enter it, then open the second door on the right. The phone is on a shelf.
Make your way up to the top deck of the barge. The phone is in a control room just before some walkways.

Venice
Proceed until you enter a small alleyway with clothes hung up to dry around it. Directly in front of you (before going up the stairs) is a walled area with a seat. The phone is on the seat.
Clear the courtyard. The gates will open. Go through them, turn left, then take the first right. The phone is on the ground next to the door.
Once past the courtyard, follow Vespa and cross the balance beam. There is a phone on a chair as soon as you cross the beam.
Kill the mercenaries, then cross the courtyard to reach to some stone stairs (bridge). The phone is on the left of the stairs in a flower bed.

Echo Hotel
Avoid the car at the start of the mission, then search in front of the burnt out car to find the phone.
Immediately after entering the underground parking garage, enter the office on the left. The phone is inside.
Go to the rear and right of the underground parking garage. There is another office with a phone inside.
After leaving the parking garage, hack the door and go inside. The phone is in the kitchen area to the right.
Leave the burning kitchen and enter the dining room. The phone is inside the closet at the far end on the right.