Five Nights at Freddy's Theories/Rumors

Phone Guy's Death

This is a big one in the fanbase, the thoery of how phone guy died.
If you have played you probably have heard the fourth night call, if not I will go over it.

Hello, hello? Hey! Hey, wow, day 4. I knew you could do it.
Uh, hey, listen, I may not be around to send you a message tomorrow. *banging sound* It's-It's been a bad night here, for me. Um, I-I'm kinda glad that I recorded my messages for you *clears throat* uh, when I did.

Uh, hey, do me a favor. *bang bang* Maybe sometime, uh, you could check inside those suits in the back room? *bang bang* I'm gonna to try to hold out until someone checks. Maybe it won't be so bad. *bang bang* Uh, I-I-I-I always wondered what was in all those empty heads back there. *chime plays*.

You know...*moan* oh, no - *noises followed by an animatronic screech and static*
As you have probably noticed, all the charaicteristics are heard, Banging on the door=Foxy, Jingle=Freddy, Groan=Bonnie/Chica, scream=Golden Freddy.
This leads to the dreaded question, who was behind his death? Many speculate that this following theory is true following GMs:
He had the left door closed, and was viewing the camera when Freddy was in the kitchen, which would have made it loud enough to catch on record, while he was in the camera, Chica snuck in and killed him, while this is very likely, it doesn't explain Golden Freddy's soundbtye, I think what happened;
The left door was closed to Foxy, and he was viewing the kitchen, but I think he glanced at the left hall, seeing Bonnie, as sometimes when viewing them you can hear groaning, and the poster was behind him, so when he put down the screen, Golden Freddy killed him, or not following GMs, all animatronics attacked him together.

What theory or rumor should I do next? Comment or message and maybe I might include it =3