Failure to Communicate

Failure to Communicate is a challenge in Borderlands 2, in the Highlandsregion. Player must shoot 4 barrel-shaped antennas located over the map. Location of the antennas:
 * On the top of the north-western tower in the large Hyperion base in the east. Can be shot from Overlook town with a sniper rifle. To recognize the right tower, look for one with hidden Vault Symbol on it, as seen from Overlook.
 * South-East of the map, at the top of a Hyperion tower.
 * From the bridge to Opportunity in south, face the exit from the map and then turn left. There is a small tower on the far shore, with the antenna on top.
 * North-East of the map, on top of the tower that is located just above Catch-a-Ride station