!!SPOILER ahead!!
Now that I've realized how Phylice talks to Walter via phone, I have a theory that Walter really has an alter personality. Because there are times in routes (not all I think), when Walter calls his mom, this is their exchange:
Phylice: "Who's this"
Walter: "It's me!"
Phylice: "Who's me?"
and conversation goes on...
I could be overthinking this, as it could just be Phylice's habit trying to ask the name of the caller everytime. But if I'm right about this, then d*mn. Walter has Dissociative Identity Disorder (Not to mention how this another personality has manifested a lot when he's pissed off)