Locate the three red rotary phones throughout the Pentagon that ring and flash. The first phone is located at the start, after opening a set of doors in the corner. The second phone is on the catwalk circling the room after leaving the first elevator. The third phone is in one of the rooms after leaving the second elevator on the floor that the power is on. You can find the phones by following their ringing. Look at the phone, then hold [Action] until you hear a busy signal. After the third phone is accessed, the song "Don't Back Down" by Eminem will play.