1st location: When you start the mission go to the room that has the Quick Revive Perk!

2nd location: You go down both elevators to the bottom floor and go to wear the power box is
and then you would see a desk and on the desk you see the red phone

3rd location: Go back upstairs to the second floor and turn on all the Defcons and then go to the pack-a-punch room and the little table when you first enter has the red phone on top.
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