Return to Sender

Return to Sender is a side quest in Fallout: New Vegas and an achievement/trophy for all platforms.

Detailed walkthrough
Speak with Sergeant Reyes at the Camp Forlorn Hope command center to begin this quest. You are asked to deliver several radio security upgrade codes by speaking to the Communications Officer at each of the Ranger stations. (If the Officer in charge was killed in any way, interact with the Ham Radio to deliver the code.)
 * Upgrade Ranger Station Alpha
 * Upgrade Ranger Station Bravo
 * Upgrade Ranger Station Charlie (if Ranger Station Charlie has already been wiped out, even though it is still stated as a quest objective, one does not need to visit it).
 * Upgrade Ranger Station Delta
 * Upgrade Ranger Station Echo
 * Upgrade Ranger Station Foxtrot

Upon returning to Reyes, she will inform you of some confusing intel reports, and you're sent back out to three stations to double-check the validity of the reports. Speak to Ranger Pason at station Delta, Ranger Lineholm at station Alpha, and Ranger Kudlow at station Foxtrot. If you've spoken to them, walk out of the tent and then back in, and speak to Reyes. After her suspicions have been justified, she asks you to go to Camp Golf and confront Chief Hanlon about it. He can be found on the balcony above the entrance to the House Resort during the day. Upon asking him about the intel reports, he tells you he wants to discuss it in a more private setting and will head to his office. The office is located on the first floor of the resort, past the front desk, and to the left of the vending machines. Once there, Hanlon will discuss his motives with you, and eventually leads to you having to make a choice. Note your choice will impact the ending you receive. Regardless of the choice you make, the quest ends there.
 * If you decide to turn him in, he will tell you to go get a ranger to make it official. Once you step out of the office, the door closes and locks, and Hanlon delivers a speech to the stationed rangers via the intercomm Once his speech is over, he commits suicide with his revolver. A nearby ranger will rush into the room to see what happened. Hanlon drops his Ranger Sequoia revolver (which is marked as owned and therefore can only be stolen with the loss of Karma), and you'll gain 500 XP.
 * Quest completed on PC and Xbox 360 by waiting outside the now-locked Hanlon office door for about one to two minutes.
 * If you let Hanlon continue his plan without informing the NCR, he tells you that you no longer have anything to discuss and walks off. You get 500XP.
 * You can choose to kill Hanlon yourself, which he warns you is a bad idea due to being in the middle of a ranger base. If you insist on doing so after his warning, Hanlon will turn hostile.
 * If you have killed Caesar, you can convince Hanlon to come back to his senses and cease falsifying the reports, and you get 500XP.

Behind the scenes

 * The quest content was implemented by Jeff Husges and Matt MacLean. Chief Hanlon was written by Joshua Sawyer.
 * "Return to Sender" is a 1962 rock and roll hit single by American singer Elvis Presley. The song was written by Winfield Scott and Otis Blackwell.