As soon as you enter a new area (one that requires a load screen) access your inventory with
, select the walkie talkie and use it with
. There are some areas where you're unable to access the walkie talkie and obviously these don't count for this achievement.
There are 5 areas required for this achievement. If you're unsure exactly where you are, make a save and it will show you the name of the location you're in.
Upuant Expedition Base - where you first pick it up
Beneath the Base