PHONE GUY
The Phone Guy was a previous security guard at Freddy Fazbear's Pizza. He helps the player by telling them about the behaviors of the animatronics at the start of each night until The 4th Night, which is his final message.
Players dispute whether or not the Phone Guy is actually an ally, saying it seems odd that he insists that they stay, and downplays the situation instead of telling them to quit or leave immediately. He may be a forced ally, but he's the only one the player has.
Personality
The Phone Guy is somewhat nonchalant, and there is absolutely no explanation as to why. Throughout the game, he does his best to inform the player that there's "really nothing to worry about," despite the obvious danger. It's unknown if he's lying to the guards out of free will, if he's obligated to do so, or just trying to make Mike Schmidt and Jeremy Fitzgerald feel better.
He seems to be very hesitant and awkward at times, often stuttering and nervously laughing, implying that he might be worried someone might be hearing him giving warnings and advice regarding the animatronics. Of course, it's also likely that he is generally anxious and on edge because of the imminent chance of death at their hands.
Dialogue
At the start of the 1st Night and up until the 4th Night, Phone Guy will call and leave a message.
FACTS:
It's quite important to listen to what he has to say on the first and second night if you are new to the game. He will give the player key hints on gameplay and the mechanics of how the game works. He is the game's version of a tutorial.
It was commonly theorized that Phone Guy is stuffed inside of Chica animatronic, as a second row of smaller teeth can be seen in her mouth, as well as the fact Chica will sometimes make very raspy, human-like groaning noises when close to the player. However, many debate that the teeth simply belongs to the endoskeleton inside the suit (as looking closely, it is possible to see the same in Bonnie's mouth), and that the rasping noises are not specific to Chica, as Bonnie is known to make the same sounds.
Likewise, some speculate that the Phone Guy was not stuffed into Chica on Night 4, but into Golden Freddy instead. Evidence to support this would be that he has a limp, lifeless body that is in a position that is commonly adopted by dead bodies while sat down.
It's also possible that the Phone Guy was stuffed into one of the heads Backstage, as he asks the player to check inside the suits in the back room and always wondered what was inside them. This heavily implies that he knew he was going to die, and knew that he would be stuffed into an animatronic suit or head.
Even when Phone Guy is talking to the player over the phone, it is important to keep an eye out for Freddy and the other animatronics (he even tells the player this himself). If the player loses focus, they'll likely get stuffed into a Freddy Fazbear suit very shortly after the message, sometimes even before it finishes.
This is notable on later nights, as remaining idle can result in Foxy killing the player before Phone Guy has finished speaking on the phone.
Scott is the one who voiced Phone Guy.
The quotation from Autobiography of a Yogi on Night 5 is from a chapter in which Yogananda posits that metal has a life force. It is possible that this is in reference to the animatronics, who are made of metal but are alive.
However, any sort of connection between the game and the sound file is very unlikely, as the garbled speech is a stock sound; this is more likely a coincidence.
It is also worth noting that Phone Guy's messages are not deleted. With all the information given, it is odd that the company has not deleted them.
In an interview with ClickTeam, Scott refers to Phone Guy literally as "Phone Guy", implying Phone Guy either has no canon name or he is keeping the character's name a secret for now.
In the phone call on Night 4, the banging sound emitted in the background is different from the one heard in-game when Foxy knocks at your left door.
In Five Nights at Freddy's, it is possible to mute Phone Guy's calls before they begin by clicking the top left corner before the "mute call" button appears.
