Immediately after starting the mission, you will find a hut on the right, with 
  a television and a 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 of that gangway at 
  the far end of the barge is a large container that has a 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.